Which of the following sentences is correct, and why?
Which of those is your cousin?
Whom of those is your cousin?
More generally, do we say "Which of those people?" or "Whom of those people?"
Which of the following sentences is correct, and why?
Which of those is your cousin?
Whom of those is your cousin?
More generally, do we say "Which of those people?" or "Whom of those people?"
I would say, who of those is your cousin (not "whom"; whom is for the object of the sentence, and "cousin" is the subject, not the object).
Which of those is also correct.
In the future, you might want to post these questions on English Language Learners.