Question

what kind of impulses do a and b carry?
section of the spinal cord with nearby skin and muscle and arrows pointing to lines going towards and away from the cord.

Explanation:

In the reflex arc diagram, A connects to the skin (a sensory receptor), so it's a sensory neuron carrying sensory impulses (from receptor to spinal cord). B connects to the muscle (effector), so it's a motor neuron carrying motor impulses (from spinal cord to effector to trigger response).

Answer:

A carries sensory impulses (from the skin receptor to the spinal cord). B carries motor impulses (from the spinal cord to the muscle effector).