A los perros no les gustan los gatos. It is definitely not D because 'se' makes absolutely no sense, and it is not B specifically because if you want a plural 'les' then you have to use a plural 'gusta', and it is not A because 'gatos' is meant to refer to cats in general.. meaning that it is not just one cat making this non-plural answer wrong. So the answer is C. I hope I helped! :D