Final answer:
Peer socialization concerning gender begins in infancy, as children engage with one another and learn social norms. Throughout childhood and adolescence, peer groups play an increasingly significant role in shaping understanding and behaviors related to gender.
Step-by-step explanation:
Peer socialization concerning gender starts early in life. In the context of the given options, it begins in infancy (Option A), when children first interact with each other and start learning the norms, such as taking turns and the rules of games on a playground. As they grow older, during their elementary school years, children's play patterns evolve from predominantly same-gender interaction to more mixed-gender groups, further advancing their understanding of gender roles through socialization. This learning process continues into adolescence, a stage associated with greater peer group influence and identity formation separate from family.
Children absorb and perform gender roles early on through four primary agents of socialization: family, education, peer groups, and mass media. This process includes playing sports like Little League Baseball or participating in groups like scouts, where cooperation, sharing, and sometimes jealousy can manifest among peers. Additionally, institutions like schools contribute to socialization, teaching societal norms beyond family influence. Such early socialization experiences significantly influence gender role understanding and behavior.