Which Answer Places the Following Events in Proper Order for Pulmonary

Which answer places the following events in proper order for pulmonary ventilation?
A: Thoracic cavity volume changes.
B: Brainstem nuclei stimulate skeletal muscles to contract.
C: Air flows down its pressure gradient.
D: Dimensional changes in the thorax lead to pressure changes within the lung.

A) b, a, d, c
B) d, c, b, a
C) b, d, c, a
D) a, c, d, b
E) c, a, d, b