The crowd washed back sudden, and then broke all apart, and went tearing off every which way, and Buck Harkness he heeled it after them, looking tolerable cheap. I could 'a' stayed if I wanted to, but I didn't want to.

Huck's words "but I didn't want to" are an example of:
(A) generalization
(B) exaggeration
(C) rationalization
(D) explanation
(E) interpretation

I'm thinking it's A.

My guess is C, but frankly, without context to understand what motivated him to follow the crowd, it is not possible to answer.

Without the whole context, C is probably correct. It's definitely not A.

=)