Physicians Routinely Give Their Patients Pulmonary Function Tests in Order

Physicians routinely give their patients pulmonary function tests in order to measure characteristics of lung function. The most common of these tests, spirometry, measures both the volume and the speed of air entering and exiting the lungs. In this test, a person first breathes normally while breathing into a spirometer, a machine that measures air volume and air speed. Then the person takes the deepest breath possible and exhales as hard as possible for 6 seconds into the spirometer. The resulting data are plotted on a graph of volume (y axis) versus time (x axis) . Spirometry is useful not only for assessing lung function in healthy patients but also for characterizing patients with lung conditions such as pulmonary fibrosis, asthma, or emphysema.
A sample graph for a healthy adult male is shown below. Normal breathing occurs between points A and B, a maximal inhalation occurs at point C, and a maximal exhalation occurs at point D. Normal breathing resumes between points E and F.

-Patients with emphysema have lungs that are less elastic than normal. As a result, they cannot exhale as much air as a healthy person can, thereby leaving additional residual volume in the lungs. How would the preceding graph differ if an emphysema patient's data were plotted instead of a healthy person's?

A) The difference in volume between points A and B would be larger.
B) The difference in volume between points C and D would be larger.
C) Point A would be at a smaller volume.
D) Point D would be at a larger volume.