Ryan realizes that his heart is beating faster than usual the moment jenna walks into the classroom. he wonders whether he has a crush on her. this reaction is best explained by the

This reaction is best explained by James-Lange theory.
Although these two scientists didn't work on the theory together, but have rather developed their own theories separately, today their results are considered to be part of one important theory about emotions. Based on their theory, feelings appear as a result of physiological reactions to events around us.

idk but if i had to take an educated guess i’d say a c d