First, let's have a think about this inertia animal, which is related to mass, ie how much stuff is in a thing. Or, if you like, more mass, more weight. Mass and weight are different but, for simplistic understanding, we can consider them to be pretty closely related. The underlying consideration to get your head around is that, for a given application of load, the greater the mass, the slower will be the response of the mass to the load. In buzz speak, we say that the acceleration of a heavier item will be slower than for a lighter item.
A simple example: you have a block of polystyrene on the floor, with a certain low mass, ie low weight, maybe 5 kg. You want to pick it up as fast as you can, with ALL your well-developed muscle strength capability, and put it on a table. So, you grab hold of it and yank it off the floor, quite rapidly, and without raising a sweat. Now, let's replace the polystyrene block with a block of hardwood with the same dimensions. Life experience tells us that the hardwood block will weigh a LOT more than the polystyrene block. Same game, you want to pull it up off the floor as quickly as you are able, using ALL your strength capability. This time, you have to grunt and groan a bit and the speed (which is related to the acceleration given to the block by your lifting activity) is MUCH slower. That is, it takes considerably longer for you to get it up onto the table. If you can get your head around this story, then you will have the basics of what inertia is doing to/for you,
Transferring this idea to aeroplanes, consider a low wing loading sailplane and a high wing loading fighter and compare their pitching motion capabilities. If the sailplane is in a dive and pulls out, we would expect to see the pitch attitude change converting into a climb fairly quickly. Conversely, for the fighter, it takes a bit longer (for a similar applied tail load change) to get the climb under way. While there is more going on than we are considering, the basic idea is that the sailplane reacts quickly because it has low inertia, while the fighter takes a bit longer due to its higher inertia. That is, the basic idea is that, for low inertia, we can do things pretty quickly while, for high inertia, it takes a bit longer to get things going, as it were.
Turning to Q2 - you are happily beetling along when, for reasons not specified, you haul back on the stick. If the aircraft has no inertia, the flow pattern changes near instantly and the aircraft starts to perform the initial stage of a loop with a negligible delay. The angle of attack has to have changed as you need an increased lift force to get the aircraft into the climb. Now, if you have a real aircraft with lots of inertia, the flow pattern will change but it takes the increased lift force a bit of time to get the aircraft into a climb. If you have a BIG aircraft, this will take longer again. That's what inertia is all about.
So the point with the question is that the stick gets hauled back, the nose starts to pitch up, the airflow changes as a consequence and, depending on the aircraft's inertia, there will be a greater or lesser time delay before the aircraft starts climbing in earnest. So, in sequence, the angle of attack will increase as the nose pitches up to give you the increased up-force to get the aircraft climbing but there will be a time delay before you see much happen, the extent of the time delay depending on the inertia of the particular aircraft.
Option (a) is OK. Option (b) is OK but would be better if it said something like ".. prevents an instantaneous/very rapid change in .." Option (c) has the cause and effect back to front, so not an option. Option (d) as for option (c). Reading between the lines, one would incline to the question's trying to get at the inertia consideration so one would prefer to opt for option (b).
Q4. In manoeuvting flight, the load factor will be changing and that is seen by the wings as a defacto variation in total aircraft weight. Weight change will vary the stall speed. Providing that you don't have a VERY high pitch rate (which changes the airflow physics) you can presume that the stalling angle will stay much the same. You can discount the other options very easily and you will be left with option (b) as the only way to go.
yet the question is asking what 'caused' the angle of attack to increase The thing you need to get your head around is that the aircraft pitches as a consequence of airflow changes at the tail but it takes a little while (depending on the mass, ie inertia, of the specific aircraft) for the aircraft to do anything in the way of starting a climb. This has to result in an increased change in angle of attack while the physics sorts out the details.
A more significant problem arises in the event that you are trying to pull out of a low level dive and you leave it too late to start the recovery. Inertia causes the aircraft to more or less continue on its initial trajectory for a while until the forces can generate adequate accelerations (inertia, again) to get the flight path changing. End result is a CFIT. Has killed many military FJ crews over the years during mishandled weapons delivery sorties.
