Which of the following sentences is positive?()

Which of the following sentences is positive？()

A.It is impossible to move forward without community support.

B.Construction can begin as soon as the building plans are approved.

C.In response to your e-mail complaint, we are investigating our agent’s poor behavior.

D.If you fail to pass the examination, you will not qualify.

请帮忙给出正确答案和分析，谢谢！