Identify the process X shown in the given figure and select the correct statement regarding it.

Options

A. During process X, air rushes out from the lungs.
B. During process X, volume of thoracic cavity decreases.
C. During process X, air pressure in the lungs decreases.
D. During process X, the diaphragm muscles relax.

Answer

C

Explanation

The process X in the given figure shows inhalation. During inhalation, diaphragm muscles contract and become flat. At the same time, intercostal muscles contract to pull the ribs upwards and outwards. This increases the volume of thoracic cavity. The lungs being elastic also increase in size and the air pressure in the lungs decreases. Air from the atmosphere having higher pressure rushes into lungs through nostrils and the lungs get filled with fresh air.