Final answer:
Peer groups play a powerful role in adolescent development by aiding in identity formation, independence, and socialization outside the family, making them a significant influence on adolescent lives.
Step-by-step explanation:
The importance of peers during adolescence is significant and multifaceted. During this period of life, adolescents typically develop an identity separate from their parents and exert independence. Peer groups become their first major socialization experience outside the familial sphere, providing adolescents with opportunities for socialization that are unique from those with their families. They also contribute to the development of moral and ethical values and increasing emotional separation from parents. With the advancement of technology and social media, adolescents are now able to broaden their peer interactions beyond their immediate physical environment, further showing the impact of peer influence.
Given these aspects, it seems appropriate to conclude that the correct answer is: 'd. They play a powerful role in the lives of adolescents.'