B. is the correct answer because apparently (from my knowledge) it is a group of words or a group of some sort. Moreover coins is a collective noun, a group of something, so yea. I hope I helped you in some sort of way and I'm sure that's correct!
Just to say you are the first one from me to answer a question because I have't been on Brainly in a WHILE! like 6 weeks. LOL.