Which of These Is a Compound Sentence

Multiple Choice

Which of these is a compound sentence?

A) Plans A and B are safe and convenient retirement programs for all workers.
B) Jill will photocopy the letters, and Adam will type the envelopes.
C) Although the data was received after the deadline, we still managed to complete the project within one week.
D) Please purchase paper clips, pencils, and notebooks when you go to the office supply store.
E) If I can buy the printer at a discount, I will; however, if I cannot, I'll wait for a sale.