Final answer:
Increased body fat tends to accelerate the onset of puberty due to the secretion of the hormone leptin by fat cells, signaling the body to initiate puberty. Conversely, lean and highly active individuals, such as gymnasts, may experience delayed puberty.
Step-by-step explanation:
The correct statement regarding the relationship between body fat and the onset of puberty is: b) Increased body fat tends to accelerate the onset of puberty. Body fat plays a role in the timing of puberty through the hormone leptin, which is secreted by adipose (fat) cells. Leptin levels appear to be instrumental in signaling the body to initiate puberty. In individuals with higher levels of body fat, such as >girls, the secretion of leptin can lead to an earlier onset of puberty.
Conversely, girls who are extremely lean and physically active, like gymnasts, often experience a delay in the onset of puberty. These findings reflect the significant metabolic demands of gestation and lactation in females. Overall, while genetics and environment also play critical roles, the presence of body fat is a significant factor in determining the onset of puberty.