Even a few trees can make it too dark for drivers to see clearly.
A.Even a few tree can make it so dark that drivers can't see the road clearly.
B. Even a few trees can make it so dark for drivers can't see the road clearly.
C.Even a few trees can make it too dark that drivers can't see the road clearly.
D.Even a few trees can make it so dark that drivers can't see the road clearly.