Question

question 4
1 pts
for a human to inhale, the rib muscles and the diaphragm must
contract, decreasing pressure inside the lungs.
relax, increasing pressure inside the lungs.
contract, increasing pressure inside the lungs.
relax, decreasing pressure inside the lungs.

Explanation:

Inhalation requires rib muscles (external intercostals) and the diaphragm to contract. Contraction of rib muscles lifts ribs upward/outward, and the diaphragm flattens, increasing thoracic cavity volume. By Boyle’s law, increased volume decreases lung pressure, drawing air in.

Answer:

A. contract, decreasing pressure inside the lungs.