We have finished the work in time __________ your help．So we are very grateful for that．Which of the following is NOT proper?

A．thanks to

B．because of

C．as a result of

D．leading to

电梯井口必须设防护栏杆或固定栅门，电梯井内应每隔两层最多隔（）设一道安全网。

A.8m

B.9m

C.10m

D.12m