[Q]: How does the sentence end?

The puppies had weak eyes but sharp ears because the 

[A]: eyes develop much slower in growing animals.


[Q]: How does the sentence end?

Megan was helping Sarah build a dark room because 

[A]: Sarah had no experience working in construction.


[Q]: How does the sentence end?

Mike's back had improved from yoga, but weight lifting was making it worse. This is due to the 

[A]:
weight lifting being more difficult.