Final answer:
Nia's choice to join the rest at McDonald's despite his personal opinion about the food being unhealthy exemplifies 'conformity', which involves changing behavior to align with the group's norms.
Step-by-step explanation:
The scenario presented, where Nia decides to go with everybody to McDonald's despite thinking it is unhealthy and not actually wanting to eat there, is an example of conformity. Conformity is apparent in this situation as it shows an individual complying with group norms or expectations. Nia does so by agreeing to go where the majority wants to go, despite personal beliefs or preferences, thereby maintaining group harmony and avoiding conflict.
In terms of social behavior, this is reflective of how individuals often modify their behavior to align with the collective choice of a group. It's an unconscious or conscious effort to fit in, sometimes even at the expense of one's own preferences or opinions. This example illustrates a broader concept where the drive to conform within a group can be strong and can influence people to act in ways they wouldn't ordinarily choose on their own.