This is a lil wow but sorry I can’t help try the internet
The correct answer is B. Indirect Characterization.
Indirect Characterization is the process by which the personality of a character is revealed through the character's speech, actions, appearance, etc.Although from this quote you don't get many details about the person speaking, you can tell what are their thoughts regarding the Burmese (which are positive thoughts) and the British (which are negative thoughts).
Probably, think about what kind of ideas dewitt had and maybe think about what vigorous means properly before u give an answer. Hope that helped a little at least. Look up each word and concentrate on what they mean. Read more about him also.