54 from bbc.co.uk for "collection comprises" 0 from bbc.co.uk for "collection is comprised of" (It may be that the BrE usage is more negative towards it)
124 from nytimes.com for "collection comprises" 4 from nytimes.com for "collection is comprised of"
This is one of those things that people have been taught are "right" and "wrong" but in the end might not actually be so. I was one of those people who was taught that the whole comprises the many, and it should NEVER be used with "of."
So, I would have said that b is wrong. But it's used so often that either it isn't really wrong, or the incorrect is just rampant and few now recog