Is it correct to say "why you pick us" in a sentence? [closed]

As titled,

Actually, we always use this sentence in a way like:

this is the reason why you pick us

rather than in a question sentence, but what I am wondering is whether it's correct to use a sentence like the above one in American or British English? Or we must use the complete sentence like

why do you pick us?

In a direct question (such as Why do you pick us?) we invert the subject and the auxiliary. Do is needed if there is no other auxiliary.

In an indirect or embedded question, which is not a sentence but functions as the subject or object of another verb, we do not invert the subject (and so we do not need the auxiliary do): This is the reason why you pick us.