Answer: Change could to can.
Explanation: Its gramatically correct in casual talk, so if not my answer then it would probably be 'no change is needed'.
I hope this helped! :)
The best resource for comparing and contrasting information on cancer diseases would be option C --The science of malignant tumors. Option A is about how to beat a specific type of cancer but it does not compare or contrast information on different types of cancer. Option B seems to be a kind of biography, which may or may not contain specific information about cancer. Option D is a medical dictionary which probably contains information about different kinds of cancer, but to use it, the reader should know what word to look up. Option C is the only one addressing malignant tumors, and therefore, it is to be expected to provide information to compare and contrast different types of cancer.
I think the answer is either d or a but im gonna go with a
