[Q]: How does the sentence end?

Dennis had a louder class than Robert did because there were more children in the class of 

[A]: Dennis .


[Q]: How does the sentence end?

Matthew is better at installing siding on houses than Randy because 

[A]: Randy doesn't work in the construction industry.


[Q]: How does the sentence end?

Emily was having difficulty going through puberty but not Christine because 

[A]:
Emily had very strong acne causing hormones.