Carson is on the swim team at his high school. He regularly dives to the bottom of the 13-foot swimming pool where he practices. While on summer vacation, Carson decides to go scuba diving off the coast of Mexico. After a few minutes descending into the deep water, his ears begin to ache. Carson wonders what is causing this pain since he never has any problems at swim practice. Why did Carson suddenly have ear pain?

a. Carson experiences more pressure while scuba diving because he has greater volume of water above him than when he dives in the pool.
b. Carson experiences more pressure while scuba diving because the particle motion of the sea water is less than the particle motion of the pool water.
c. Carson experiences more pressure while scuba diving because the temperature of the sea water is colder than temperature of the pool water.
d. Carson experiences more pressure while scuba diving because the density of the sea water is less than the density of the pool water.