boyle's law represents the relationship of volume as pressure changes. the constants of boyle's law are:
pressure and number of molecules of gas
volume and temperature
pressure and temperature
temperature and number of molecules of gas
pressure and volume

D. pressure and volume

Explanation:

Boyle’s law states that,

For a given amount of a gas, Pressure is inversely proportional to its volume at constant temperature

Thus the expression is

PV = constant (T and n are constant)

When there is a change in pressure and volume we make use of the expression  

(T and n are constants)

Where and are the Initial pressure and volume and

and are the final pressure and volume

Inversely proportional means when one increases the other one decreases. That is as per Boyle’s law when Pressure increases the volume will decrease and vice versa.

o conteúdo de calor de um sistema é igual à entalpia apenas para um sistema que é constante