I believe your answer is A because almost all people with knowledge know that grass is green. Someone would only ask this if they weren't for sure, such as someone being color blind. Hope this helped!
It is "Is Grass Green?" because a Rhetorical Question is a question you ask that you wouldn't expect someone to answer but also the question is one that might have an <span>obvious answer but you have asked the </span>question<span> to make a point, to persuade or for literary effect. In other words it might be a question people could call </span>stupid like "Do birds fly?" because obviously birds fly.
