The clinic nurse is caring for a patient who has been diagnosed with emphysema and who has just had a pulmonary function test (PFT) ordered. The patient asks, "What exactly is this test for?" What would be the nurse's best response?

A PFT measures how much air moves in and out of your lungs when you breathe.

A PFT measures your oxygen saturation.

A PFT measures whether oxygen and carbon dioxide is balanced with an appropriate pH.

A PFT measures whether oxygen and carbon dioxide move between your lungs and your blood.