Answer:
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.
