What is the main process that enables breathing?

What is the main process that enables breathing?
  1. Movement of air into and out of the lungs
  2. Pressure gradient between the lungs and the atmosphere
  3. Negative pressure in the lungs with respect to atmospheric pressure
  4. Intra-pulmonary pressure higher than atmospheric pressure

Solution

Breathing involves two stages: inspiration and expiration, which is enabled by the movement of air into and out of the lungs.

Asked in: NCERT

Practice more Breathing and Exchange of Gases questions on Aicharya