Which of these is an example of a compound sentence?

a.
Fast food isn't likely to be the best choice for a health-conscious consumer.
c.
neither of these
b.
Gwen was taking three science courses this semester, yet she was able to maintain straight A?s.
d.
both of these


Please select the best answer from the choices provided

A
B
C
D

b. Gwen was taking three science courses this semester, yet she was able to maintain straight A?s.