“函数f（x）在x₀处取得极值”是“f′（x₀）=0“的（　　）

A．充分不必要条件

B．必要不充分条件

C．充要条件

D．既非充分又非必要条件

— Where is Jack?

— He ______ basketball on the playground.

[      ]

A. plays

B. is playing

C. is going to play

D. play