以下句子哪个是号召性句型?

以下句子哪个是号召性句型?

A.It is prime time that we put considerable / great/ special emphasis on …

B.The best way to solve this problem I think is to give young people opportunities to do things independently.

C.It is, therefore, evident that the task of … requires immediate attention.

D.The general awareness of the necessity and importance of ... might be the first step to solve this problem.

正确答案是A