The Internet is regarded as one of the reasons many people aren’t getting enough sleep now

问题补充：

The Internet is regarded as one of the reasons many people aren’t getting enough sleep now．

A. which

B. what

C. as

D. why

答案：

A. which

B. what

C. as

(答案→)D. why

解析：定语从句考查题。先行词为the reasons关系词why在从句中做状语。