The correct answer is C. Labeling theory
Step-by-step explanation:
In sociology, deviance occurs as an individual's actions or behavior are against social norms. This phenomenon is widely studied in sociology from multiple perspectives, one of these is the labeling theory. In the labeling theory, individuals define themselves based on the terms and words other people use to refer to them, which models their behavior, actions and who they are. This occurs in the case presented because as other people refer to the child as "slow" this label defined his behavior and made him drop out of school as he considered he was not smart. Thus, the case presented is an example of Labeling theory.