Final answer:
The term for someone supportive and reliable in a group is a team player, and an example of a leadership prototype on an athletic team is the team captain. Groups can influence individual behavior through norms and values, often referred to as a reference group.
Step-by-step explanation:
The term for someone who is considered to be a supportive, reliable part of a group is a. Team player. This individual actively contributes to the group's objectives and works well with others, providing support and reliability which are essential for the cohesion and success of the group. In the context of an athletic team, the prototype for leadership would be c. the team captain, who embodies not only the role of a leader but also sets a standard for teamwork and sportsmanship.
In terms of social structures, a group whose values, norms, and beliefs become a standard for an individual's behavior is identified as c. Reference group.
It is important to recognize that individuals can exhibit different leadership styles within a group setting. One such style is that of a democratic leader, who promotes participation and strives to build consensus before making group decisions, though this process can sometimes be time-consuming and risk creating factions within the group.