HELP FAST PLEASEE

Which identifies the compound sentence that is punctuated correctly?

A. Once each year Assateague firefighters round up the ponies, and some are sold at auction.

B. Once each year Assateague firefighters round up the ponies and sell some at auction.

C. Once each year Assateague firefighters round up and sell some ponies at auction.

D. Once each year Assateague firefighters round up the ponies, set up an auction, and sell some.