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 the reason is a correct explanation of the assertion
B. If both the assertion 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

A

Explanation

According to All or none principle the stimulus below threshold do not generate nerve impulse and above it generate nerve impulse with same strength but this law does not follow to muscle cell. Thus each muscle cell activates and thus increase strength of contraction of muscle.