[Q]: How does the sentence end?

Derrick asked Leslie for advice on how to avoid bankruptcy, because 

[A]: Derrick is bad at managing money.


[Q]: How does the sentence end?

Matthew knew that their ring contained real diamonds but Derrick did not because 

[A]: Matthew was an expert on gemstones.


[Q]: How does the sentence end?

Robert used their camera to take a picture of Michael, because 

[A]:
Michael was a good subject.