Why Do Scuba Divers Exhale Air When They Ascend to the Surface

Multiple Choice

Why do scuba divers exhale air when they ascend to the surface after a dive?

A) The air bubbles which surround the diver as he/she exhales assists overall buoyancy making it easier for the diver to ascend.
B) Exhaling of air decreases the volume of air in the lungs, thus making it easier for the lungs to adjust to the decrease in external pressure on the diver as the diver ascends.
C) If the air in the lungs were not exhaled, the volume of air inside the lungs would expand as the diver ascended and could severely damage the lungs.
D) Both B and C are true.
E) None of the above are true.