Which describes the role of the diaphragm during inhalation?

A The diaphragm flattens, making the chest cavity smaller, and air is sucked in.

B The diaphragm moves upward, making the chest cavity smaller, and air is pushed out.

C The diaphragm flattens, making the chest cavity larger, and air flows in.

D The diaphragm moves upward, making the chest cavity larger, and air flows in.