"Café Olympia serves coffee from all over the world" (B) states a fact rather than an opinion.
When writing essays for school, or researching information to support your writing, it is important to be able to stay factual and avoid stating opinions (unless you are specifically asked to do it, or unless you explicitly mention that you are quoting a biased work).
These characteristics should help you identify an opinion:
Conversely, a factual statement usually has: