I've been wrestling with a few particularly tricky necessary assumption (NA) questions (PT116.S2.Q16 and PT127.S2.Q20) where I find myself quite unconvinced with the right answer. I won't spoil those qs in particular, but spending some time with them + re-reading a prepbook section on NA questions has gotten me to the following understanding:

Steps for NA assumption q (e.g. "which of the following must be assumed for the argument to hold"):

1. Identify the conclusion (C) and support (S).

2. Roughly identify the gap/weak point between C and S.

3. Go through each answer choice -- which one is required for the argument to hold?

More on step 3:

Step 3 is where I've gotten tripped up. A straightforward reading of "which one is required for the argument to hold?" = "If the assumption is false then the argument does not hold." i.e. negate the answer choice, and check if the argument is destroyed. I think this works the majority of the time but requires a little more nuance for some qs.

There are times where "if the assumption is false then the argument is severely weakened (but not destroyed)" seems to be the correct answer. (Another tricky nuance is that the assumption could be needed, not sufficient enough on its own to fill the gap in the argument and still be the correct answer).

What seems to never be the correct answer is an answer choice that goes beyond what is required.

The reason I find this confusing is that you could be faced with two ACs (and I contend PT116.S2.Q16 and PT127.S2.Q20 are examples of this) where neither of two answer choices seems to be strictly necessary, but the narrower one is correct.

Would appreciate any thoughts/pushback on this!!