A reflex arc occurs when: Select one: a. a sensory nerve sends a message to the brain but the motor nerve fails to send the appropriate response to the body. b. the motor nerves function automatically without receiving a message from the CNS. c. the brain interprets sensory information that it receives from peripheral and cranial nerves and sends a signal to the muscles. d. a sensory nerve detects an irritating stimulus and bypasses the brain by sending a direct message to the motor nerve.

Option-D

Explanation:

A reflex arc is the neuron pathway which is involved in producing the response to reflex action or the immediate response.

The reflex arc pathway involves the sensory neurons, interneurons and the motor neurons. Although the reflex arc pathway involves the brain later but in producing response the brain is not involved.

The stimuli are perceived by the spinal cord but not the brain therefore the selected option is correct.

Thus, option-D is correct.

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