Question

What type of social media site uses a community knowledge to solve a users query?

a) online market

b)social book marketing site

c) social news site

d)online forum

Answer 1

I think its a i'm not sure tho 

Answer 2

An online forum.
All the other answer choices aren't related to answering a question.

For example, online market sells stuff. Social book marketing site sells stuff. Social news site promotes news.
Only an online forum allows members to discuss topics and ask/answer questions.