"Do we learn from history?"

A: Of course, but not as fast (or permanently) as many of us would prefer, and it's hard to see progress when we look at it within the frame of reference of our own life span.

Zoom out to a century-long measure, and the progressive trend is obvious.

It is grievous to be caught in the inevitable pendulum swings, as targets ourselves or as folks loving the targeted. Thus, sentence A.

~S~