As you to sit there studying, you are unlikely to be aware of the pressure of your clothes against your body and the rustling paper as other students turn pages. Which part of the brain "decides" that these are unimportant stimuli? a. reticular activating system

b. cerebellum

c. hypothalamus

d. medulla

A) Reticular activating system

Explanation:

The reticular activating system is a complex network of neuron present in the brainstem of the brain.

The reticular system is involved in many functions of the brain like the flight or fight response, the sleep and awake awareness and the elimination of the unwanted and unimportant stimuli of the person.

In the given question, since the person, while studying unconsciously avoids the rustling of paper and the pressure of the clothes which is performed by the reticular system in the brain.

Thus, Option-A is correct.