Which of the Following Statements Is True Regarding the Normal

Multiple Choice

Which of the following statements is true regarding the normal mechanism of ventilation?

A) There must be a continuous column of air from the pharynx to the alveoli.
B) The lungs must lie within a sealed-off thoracic cavity.
C) The inner and outer pleural membranes must be separated by a thin film of fluid.
D) The diaphragm, when contracted, will be lowered.
E) All of the answer choices are true.