If a diesel engine starts firing, but is unable to come up normal speed, either without lo

If a diesel engine starts firing, but is unable to come up normal speed, either without load or even under a small load, the cause may be ___________.

A.insufficient fuel supply

B.faulty governor

C.high exhaust back pressure

D.all of the above may cause this problem

请帮忙给出正确答案和分析，谢谢！