Which one is correct?
If I ask "What's your favorite animal?"
A: My favorite animal is dogs.
B: My favorite animal are dogs.
C: My favorite animals are dogs.
by the way, I know the best answer is "Dogs are my favorite animal."

Question

Answer

My favourite animal is the dog.
My favourite animals are dogs.
Dogs are my favourite animals.

Answer

-C-
A is incorrect because you said dogS
B is incorrect because you said "animal" are
C is the best answer.
better to say :
My favorite animal is the dog .
*And note that you are talking about dogs in general so there is no need to say dogS.  because you are not talking about a dog or many dogs.

Answer

animal 单数指一类物，我觉得My favorite animal is the dog 特指狗，前面animals的话，后面就接are the dog and the cat