Anton thinks he is intelligent and good at math. when he starts taking an advanced placement calculus class he realizes all the students are incredibly smart and they all excel in the class. anton thinks to himself, "wow, compared to these students, i am not as smart as i thought." anton's statement reflects an immediate sense of his own identity in this situation, which is called

Working self-concept.

Explanation:

Working self-concept is defined as activation of self perception due to exposure towards any event or experience that signifies than an individual has certain circumscribed personal information about their own-self in terms of characteristics, thought , abilities,etc.

According to the question,Anton is also signifying working self concept.He though that he is intelligent in math but after getting exposed to other students in calculus class he got to know that other students are exceptionally intelligent  and smart.

Thus,after realizing this situation ,Anton immediately created a self perception about himself.