Final answer:
The characteristic that is not typically associated with youths during middle adolescence is that they are less concerned about their changing bodies.
Step-by-step explanation:
The characteristic that is not typically associated with youths during middle adolescence is c. They are less concerned about their changing bodies.
During middle adolescence, which is roughly between the ages of 14-17, youths often experience heightened self-consciousness and are more concerned about their changing bodies. They may compare themselves to their peers and feel self-conscious about physical appearance.
In contrast, the other characteristics listed are commonly observed during middle adolescence. Youths become more assertive in asserting their independence, experience continued growth (both physical and psychological), and are heavily influenced by peer group pressure in their thinking and life choices.