My best bet would be C or D most likely C
I think the dominant irony presented in the passage would be :
The Houyhnhnms. the most rational beings on earth, are discussing the extermination of an entire group of creatures.
You can see that in this sentence, the second part of the statement contradict the statement on the first part.
Geometric.................
<span>Early biographies tended to criticize or praise the person. Good biographies today are nonjudgmental.</span>
