Question

multiple choice question
when the diaphragm _____, the thoracic cavity _____.
o relaxes; enlarges
o contracts; enlarges
o contracts; becomes smaller

Explanation:

When the diaphragm contracts, it moves downward. This action increases the volume of the thoracic cavity (enlarges it). When it relaxes, it moves upward, decreasing the volume of the thoracic cavity.

Answer:

contracts; enlarges