Facebook may be the worst company to interview for in the Bay Area when it comes to engineering. Facebook seems to hire engineers almost exclusively from two demographics: White and Asian. If you don't belong, do yourself a favor and do not waste time interviewing with them. Facebook won't hire you. Not only that, engineers conducting interviews will put you under more scrutiny than they would other candidates. You will be at a disadvantage from the first question. Simply put, they are not used to hiring engineers from your background and will set you up to fail the interview, a self-fulfilling prophecy.

My advice to Facebook is to, in general, train your engineers well regarding unconscious bias and have them certify before allowing them to conduct interviews. In particular, I would add a rule: do not let engineers on sponsored visas who have been in the country for only a short time conduct interviews for citizens and permanent (green card) residents, as they do not yet understand the race dynamics of the U.S.A. It just does not feel right. It would be fine to let them conduct interviews for other candidates seeking visa sponsorship, though.

Not relevant, even if you answered correctly. (See my comment)