Final answer:
Behavioral groups like those comprised of Type A individuals are characterized by a direct approach. A reference group strongly influences an individual's behavior by setting norms and expectations for conformity.
Step-by-step explanation:
This is one of the behavioral groups, characterized by a direct and no-nonsense approach to people. Such behavioral tendencies can be attributed to Type A individuals, as described in figure 14.18 from your materials, who are often intensely driven and goal-oriented. This contrasts with Type B individuals who are characterized as more laid-back and relaxed.
When considering group dynamics and behavior, it's also important to understand the concept of a reference group, which is a group whose values, norms, and beliefs come to serve as a standard for one's own behavior. Reference group is the answer to your multiple-choice question (Option c). This group plays a significant role in shaping an individual's behavior and decision-making process, often unconsciously influencing them to conform to group norms to gain approval or to avoid disapproval from group members.