I would say “The colorful rings on the Olympic flag have symbolic meaning”
You can either use process of elimination, or look at the last answer choice and see how it states the main idea of the article and is simple.
A would be wrong because the question isn’t very intriguing, which would be the main point of the question!
B wouldn’t make sense because that wouldn’t be a topic sentence, it’s just a question ig?
C would be wrong because that’s just a fact, not the main purpose of the article