The answer is C.
Reason being:
A. This is incorrect because the passage doesn’t state anything but recycling being difficult to do, therefore, it can’t be a topic option.
B. Now this one is alright, BUT it mentions “garbage problem” and the passage is mainly using the word “recycling”. It COULD’VE been a topic, but it isnt spot on when you look at C.
D. The passage doesn’t mention this and if it were to, it wouldn’t have been the MAIN topic because everything is focusing on multiple benefits.