What intestine is a tube about 10-13 feet long folded inside of the human body

Which of the following are considered general purposes of performing pulmonary function tests (pfts)? 1. the functional status of the lungs 2. the diffusion characteristics of the alveolar-capillary membrane 3. how much and how fast gas can be moved into and out of the lungs 4. the specific diagnosis of pulmonary disease