- A Relaxing and moving up
- B Contracting and moving down
- C Staying still
- D Moving sideways
Correct answer: B. Contracting and moving down
Explanation: During inhalation, the diaphragm contracts and flattens (moves down), increasing chest volume, decreasing pressure, and drawing air in.
Concept context
The mechanics of breathing, lung volumes, gas transport in blood, the Bohr effect, and respiratory regulation.