Final answer:
The most marked fluctuations in self-image occur during adolescence due to the psychosocial changes that take place.
Step-by-step explanation:
The most marked fluctuations in self-image occur during adolescence. This is supported by research studies that have found that teenagers develop a stronger sense of personal identity and a greater awareness of body image during this period. Adolescents also experience changes in their relationships, spending more time with peers and experiencing a desire to conform to their peer group. These psychosocial changes, along with the physical changes of puberty, contribute to the fluctuations in self-image that occur during adolescence.