Question 4: You are too slow. I’m sure that by the time you phone them

Question 4: You are too slow. I’m sure that by the time you phone them, they ______ that car to someone else.

• A. will sell
• B. will have sold
• C. are going to sell
• D. are selling

By the time + S + V(hiện tại đơn), S + V(tương lai hoàn thành).