Figure 23-2 Mechanics of Ventilation

Use Figure 23-2 to answer the following questions:
-How does the pressure "P4" at label "4" compare to the pressure "P5" at label "5"?

A) P4 is higher than P5 during inhalation and then lower during exhalation.
B) P4 is always higher than P5.
C) P4 is always lower than P5.
D) P4 always equals P5.
E) P4 is lower than P5 during inhalation and then higher during exhalation.