@shrooots I think the idea is we are intentionally moving slower than necessary to build the habit of doing these analyses. It will become much faster for us and second nature, almost subconscious, over time. Like a guitarist learning to play a solo slowly at first.

For those that like me were confused because A) doesn't have chaining logic. The underlying flaw pattern between Stim and A is still the same, here's why:

Stim:

A -> C (the chaining A->B->C functions this way)

-----------

C^ , A^

Answer A:

X -m-> A (I think of this as just context to ignore, doesn't effect flaw pattern)

A -> C (Contra positive of /C -> /A)

-------

C^ , A^

I got lucky and just started by reading A, thought "well that's obviously necessary" and submitted it w/o bothering to read any other answers. Totally would have fallen for B