Because he lives in the fraternity house, Carl finds it hard to eat a low-fat diet since his housemates think such a diet is unmanly. According to the theory of planned behavior, Carl's interpretation of his fraternity brothers' views and his failure to eat what he knows is a healthier diet is being influenced by:

Subjective norm.

Explanation:

The theory of planned behavior seeks to explain any health behavior over which the individual has control. It believes that behavior is influenced by a number of factors such as pressure from family or society, the belief that changing that behavior will be easy or difficult, the belief in one's own capacity to do it etc.

According to this theory, there are six constructs that represent a person's actual control of a certain behavior. One of those constructs is called subjective norm. It refers to the person's belief concerning whether or not that behavior is approved by others. If a person believes people who are important to him do not want him to engage in a certain behavior, he will be less likely to do it. That is Carl's situation. His lack of conviction concerning his diet comes from a subjective norm.

why does the crew join ahab's quest without hesitation?