When sam walks into his class, he does not have to think consciously about how to walk. when he gets there, he pays attention to the lectures even if they are boring or he is tired. in this scenario, the brain structure that is most likely causing these stereotyped patterns of behavior in sam is the?

The answer to this question is:

The brain structure that is most likely causing this is the “Reticular Formation”.  

The reticular formation plays a vital role in states of consciousness like awareness and sleep. It has connections to the thalamus and cerebral cortex that allow it to gain some control over which sensory signals arrive at the cerebrum and come to our conscious attention. 

Ithink it's c selection but i don't really know.