Which of the following best describes the relationship between pressure and volume of a gas?

The correct choice highlights that the relationship between pressure and volume of a gas is inversely proportional, which is a fundamental principle in physics known as Boyle's Law. According to Boyle's Law, if the temperature of a gas is held constant, when the volume of the gas increases, its pressure decreases, and vice versa. This means that for a given amount of gas at constant temperature, if you compress the gas (reducing its volume), the pressure will increase, and if you allow the gas to expand (increasing its volume), the pressure will decrease.

This relationship is crucial for divers to understand, as it affects how gas behaves when under different pressures underwater. For instance, as a diver descends, the increasing water pressure compresses the air in their lungs, significantly lowering the volume of the air. Conversely, as a diver ascends, the decrease in pressure allows the gas to expand, which must be managed carefully to avoid injury.

The other choices do not accurately describe this relationship. Saying they are directly proportional would imply that pressure and volume increase or decrease together, which is not the case. Claiming they are unrelated ignores the critical connection defined by Boyle's Law, and stating they remain constant would indicate equilibrium under all circumstances, which is