I believe the correct answer is C. written and signed.
Given that deaf people cannot hear, spoken literature wouldn't really do much for them as they won't be able to hear it. This means that you can eliminate options B and D immediately. When it comes to A, ASL stands for American Sign Language, which is the same as signed language, so you don't have to mention the same thing twice, which means that you can also eliminate A. This leaves us with C as the correct answer, as deaf people use sign language, and they can read.
