In research essays, brackets [ ] are used by writers to demonstrate when
a) original sources have been paraphrased
b) small changes have been made within exact quotations
c) outside resources have been cited
d) parts of a quotation were already within quotation marks

B) small changes have been made within exact quotations

Explanation:

Brackets are pair of marks [ ] which enclose words or figures in order to separate them from the context. In essay writing, sometimes a quotation does not fit exactly within the author's text because of capitalization, the use of other words or structures, or because part of the quotation is wished to be omitted. Therefore, the use of brackets indicate that the quotation's exact punctuation has been adapted to the punctuation or grammar structure of the essay. For example:

Original quotation: "That's one small step for a man; one giant leap for mankind."

Essay writing: Before landing on the moon, Neil Armstrong says "[t]hat's one small step for a man [...]" and then he sets foot on the ground.

answer; i believe the correct answer is ( indirect characterization);