A. The diaphragm moves downward
B. The rib cage is compressed
C. The thoracic cavity volume decreases
D. The ribs and sternum move upward
The intercostal muscles are muscles are located along the ribs. The intercostal muscles assist in respiration mechanically. This allows the expansion and contraction of the thorax.
Contraction of the external intercostal muscle causes the ribs and sternum move upward.
Therefore, the Correct Answer is D.