—I'm sorry. That wasn' t of much help.

—Oh, （）.As a matter of fact, it was most helpful.

A.sure it was

B.it doesn't matter

C.or course not

D.thanks anyway

如图所示的两个力的图示，比较它们的大小，则（　　）

A．F_l=-F₂

B．F₁＜F₂

C．F₁＞F₂

D．无法判断它们的大小