Choose the sentence that best connects the two sentences below using a proper relative pronoun.

I know the boy.
His mother works as a doctor at a nearby clinic.

A. I know the boy whose mother works as a doctor at a nearby clinic.

B. I know the boy who mother works at a nearby clinic.

C. I know the boy which his mother works at a nearby clinic.

D. I know the boy who he mother works at a nearby clinic.