Final answer:
Pressure diagrams will be the same if the temperature is constant, according to Boyle's Law, which relates pressure and volume of a gas at constant temperature.
Step-by-step explanation:
The question asks why pressure diagrams would be the same. The answer to this lies in understanding the relationship between pressure, volume, and temperature of a gas. According to Boyle's law, when the temperature of a gas is constant, the product of the pressure and volume will remain constant. On a pressure diagram, if the temperature stays consistent and the volume does not change, the pressure must stay the same as well.
That is to say, within the context of the given choices, the best match would be B) Because the temperature is constant. This is because Boyle's Law states that P1V1 = P2V2, where P1 and V1 are the initial pressure and volume, and P2 and V2 the final ones, as long as the temperature and the amount of gas don't change.