Boyle's law represents the relationship of volume as pressure changes. the constants of boyle's law are:

a. pressure and number of molecules of gas
b. volume and temperature
c. pressure and temperature
d. temperature and number of molecules of gas
e. pressure and volume

d. Temperature and number of molecules of gas  

Step-by-step explanation:

Boyle's Law states, "The volume of a fixed mass of a gas is inversely proportional to the pressure if the temperature remains constant."

Let's examine the words.

"… volume…is inversely proportional to the pressure …" This means that volume and pressure are the variables.

"… fixed mass of a gas …" means that the number of molecules is constant.

"… temperature remains constant" speaks for itself.

a, c, and e are wrong, because pressure is a variable.

b is wrong, because volume is a variable.