Which is a correctly punctuated COMPOUND sentence?

Responses
A The girl ran across the street and got the mail.The girl ran across the street and got the mail.
B The girl ran across the street, and she got the mail.The girl ran across the street, and she got the mail.
C The girl ran across the street because she wanted to get the mail.The girl ran across the street because she wanted to get the mail.
D The girl ran across the street, got the mail, and returned to the house.

D The girl ran across the street, got the mail, and returned to the house.