Assertion: The contraction of diaphragm and external intercostal muscles is necessary for inspiration during breathing.
Reason: The contraction of these muscles increases the volume of the thoracic chamber, creating a pressure gradient that allows air to flow into the lungs.
Both the Assertion and Reason are true, and the Reason is the correct explanation of the Assertion.
Both the Assertion and Reason are true, but the Reason is not the correct explanation of the Assertion.
The Assertion is true, but the Reason is false.
The Assertion is false, but the Reason is true.
The given assertion states that the contraction of the diaphragm and external intercostal muscles is necessary for inspiration during breathing. The reason provided explains that the contraction of these muscles increases the volume of the thoracic chamber, which creates a pressure gradient. This pressure gradient allows air to flow into the lungs. The reason accurately explains why the assertion is true making option 1 the correct answer.