a ou b ?

Choisissez la solution qui convient. (Ø = rien) 1. He was the only person a. that / b. who I didn’t know. 2. I’d like to know the cook a. which / b. who got dinner ready. 3. That pretty actress a. Ø / b. which you like so much is married! 4. The girl a. who(m) / b. which you spoke to was very good-looking. 5. This is the first thing a. which / b. that you should do. 6. I can’t see a. whose / b. why I should give you my phone! 7. You’re the candidate a. whose / b. Ø we’re going to choose. 8. Sylvia, a. whose / b. Ø books are bestsellers, is a charming girl