Which correction should be made to sentence 7?

— ExhibitC

— Exhibit -Sentence 7:Let us order them for you because at a discount you are a member.

Which correction should be made to sentence 7?
A . replace because with for
B . insert a comma after because
C . replace because at a discount with at a discount because
D . insert a comma after discount
E . no correction is necessary

Answer: C