Question

---Could I use your phone?

---_________．

1. A.
   Yes, you may use
2. B.
   Yes, you could
3. C.
   Yes, help yourself
4. D.
   Yes, go on

Answer 1

C
help yourself意为“自便”，此处相当于go ahead; could作情态动词时，答语中则用can代替问句中的could。could在本句中指一种语气，而不表示时态。