HELP!
Which of the following is a complex sentence?

Although Jason and Harriet hurried down to the shore, they arrived too late to see a. A. the sailors.
B. Harriet told Jason to hurry up. The sailors were going to leave the harbor and travel far away.
C. Jason and Harriet hurried down to the shore, and the sailors floated off into the distance.
D. Jason and Harriet hurried down to the shore and watched the sailboat into the distance.