Final answer:
The statement about changes in social crowds during adolescence that is not true is that crowds become more homogenous; instead, they become more specialized.
Step-by-step explanation:
Over the course of adolescence, the statement about changes in social crowds that is not true is (a) Crowds become more homogenous. Developing social identities often leads to individuals seeking out diverse groups or crowds where they can feel a sense of belonging or share interests. During adolescence, crowds tend to become more specialized, and as such, individuals may naturally move between them (b) or witness crowds merging or disintegrating (c).
Furthermore, crowds usually do not become less influential (d); on the contrary, they often remain significant sources of social influence and peer pressure during this stage of life. Adolescents may join different crowds for a range of reasons, such as shared activities, goals, or to gain social status, indicating the ongoing influence that crowds can exert on individual behavior.