Which of the following is a compound sentence? George took one last look around the apartment; every stain on the carpet called up another happy memory of freshman year. The roommates argue over the cause of the stains. Because he is an optimist, Tony suggests they could rearrange the furniture to hide the carpet stains, but no one else thinks the landlord would be fooled. Tom hopes he can get his security deposit back even though the stains on the carpet make it a long shot.