Which of the following is a compound-complex sentence?
a. mariella and her sisters always remember to turn off their cell phones in a movie theater.
b. mariella and her sisters went to the movies, and as they sat down, mariella reminded her sisters to turn off their cell phones.
c. as mariella settled into her seat at the movie theater, she reminded her sisters to turn off their cell phones.
d. people who turn off their cell phones at the movie theater are respectful of other people in the theater.