Assertion : Muscle contraction force increases with rise in strength of stimulus.
Reason: This is due to increased contraction of individual muscle fibres with increases in stimulus strength.

Options

A. If both the assertion and the reason are true and reason is a correct explanation of the assertion
B. If both the assertioin and reason are true but the reason is not a correct explanation of the assertion.
C. If the assertion is true but the reason is false
D. If both the assertion and reason are false

Answer

C

Explanation

The muscle fibre always contracts with the maximum force and this force doesn't rise on increasing the strength of the stimulus. If the stimulus is of strength below the thereshold, then the muscle fibre doesn't contract at all. This is known as All or None law. But the entire muscle doesn't obey this law, it means that force of contraction of muscle increase with rise in strength of the stimulus. this is due to the fact that the strength of the threshold stimulas varies from muscle fibre to muscle fibre in a muscle.