Name the given structure. What is its general function? Mention the function of the parts labelled as A and B. These structures in animals are said to be efficient ways to give quick responses. Why?

Explanation

The given structure is Reflex arc (spinal cord). It gives sudden action in response to the event happening in the environment.
Part A - Sensory neuron: It conducts the impulse of stimulus from receptor to the spinal cord.
Part B - Effectors: Which shows the sudden visible response.
Reflex arcs have evolved in animals because the thinking process of brain is not fast enough in many animals. Mean while many animals have very little of the complex neuron network needed for thinking. So it can function in the absence of true thought process and increase the chance of survival.