The first diagram depicts a spirometer, an instrument used to measure changes in lung volume. During exhalation, the cover moves up, and during inhalation it moves down, creating a record on a rotating drum. The second diagram shows a typical spirometer trace. Which trace would show the vital capacity?
- A$X + Y$
- B$X - Y$
- C$X + Y + Z$
- D$X - Y + Z$