Which verb best completes the question:
¿cuántos perros en la casa?

va

son

hay

fue

The verb that best completes the question: ¿Cuántos perros hay en la casa? es: "Hay"/are

Explanation:

First of all the question asks about some dogs in a house. So:

Va is a verb that translates to go in English and our case is conjucted in singular not plural. So it's wrong because we are talking about dogs not a dog.

Son is a verb that translates to are in a form of being and plural this could be a good option. But it's incorrect because the proper question to ask about the number of dogs in a certain house should be "hay" of having because they are objects not persons, and son is a verb to represent a state of being.

Hay is the correct answer because we translate "Hay" like are in a way of having. We don't talk of dogs as persons but as objects. Also it is conjuctedin plural.

Fue is a verb that translates to went and we are reading the sentence in present so past verb is wrong.