A blank is the way a person reacts to a situation based on the social environment in which a person grows up.

A. Coping strategy
B. Defense mechanism
C. Learned emotion
D. Primary emotion

C. Learned emotion

The correct answer is C. Learned emotion.

To arrive at this answer, we need to understand the definitions of each option and eliminate the incorrect ones:

A. Coping strategy: A coping strategy refers to the actions or behaviors that individuals use to deal with stressful situations or emotions. While the social environment can influence coping strategies, it does not directly reflect how a person reacts to a situation based on the social environment they grew up in. Therefore, this option is incorrect.

B. Defense mechanism: Defense mechanisms are psychological strategies that individuals use to protect themselves from anxiety or discomfort. While defense mechanisms can be influenced by the social environment, they do not directly represent a person's reaction to a situation based on the social environment they grew up in. Hence, this option is also incorrect.

C. Learned emotion: Learned emotion refers to an emotional response or reaction that is acquired through socialization or cultural norms. It suggests that emotions are not purely innate but also shaped by the social environment individuals grow up in. This option aligns with the given explanation, making it the correct answer.

D. Primary emotion: Primary emotions refer to a set of basic, universal emotions that are believed to be instinctive and experienced by individuals regardless of their cultural or social backgrounds. Although primary emotions play a role in a person's reaction to a situation, they do not specifically address how the social environment influences that reaction. Therefore, this option is incorrect.

In conclusion, the correct answer is C. Learned emotion, as it accurately describes the way a person reacts to a situation based on the social environment in which they grow up.