Choose the best sentence that can be made from the cues given

Choose the best sentence that can be made from the cues given.     
1, we/look carefully/right/left/crossing/roads. 
A, we must look carefully right or left after crossing the roads 
B, we must look carefully right or left before crossing the roads 
C, we must look carefully right and left after crossing the roads 
D, we must look carefully right and left before crossing the roads