grammaticality - Use of “What kind”, and “What kind” vs “Which kind”

If we want to know the exact kind of a group of brids, should we say:

A: "What is the kind of these birds?"

or

B: "What kind of birds are these birds"?

If the questions above are phrased correctly, then there is a new question raised. Suppose there are three kinds of birds: A, B, and C, and the kind C is facing extinction. If we want to know the name of the kind that is facing extinction, how should we ask:

A: What kind of birds is facing extinction?

or

B: What kind of birds are facing extinction?

or

C: Which kind of birds is facing extinction?

Which one is correct?