[Q]: How does the sentence end?

The screw put a deeper scratch in the wall than the nail, because the 

[A]: nail was duller.


[Q]: How does the sentence end?

Monica only listened to the radio and never watched TV unlike Emily because 

[A]: Emily had a radio and TV.


[Q]: How does the sentence end?

Benjamin has whiter teeth than Jason because 

[A]:
Jason does not use a toothpaste with baking soda in it.