Which of the following best describes the thermodynamic effect on the pressure and volume

Which of the following best describes the thermodynamic effect on the pressure and volume relationship with regards to saturated gases？

A.As pressure decreases, volume increases

B.As volume increases, pressure increases

C.As volume decreases, pressure decreases

D.AS pressure increases, volume increases

请帮忙给出正确答案和分析，谢谢！