## Core Concept
The onset of puberty is influenced by a complex interplay of genetic, hormonal, and environmental factors. The difference in the age of onset of puberty between males and females can be attributed to variations in the timing of hormonal changes. Specifically, the hypothalamic-pituitary-gonadal axis plays a crucial role in initiating puberty.

## Why the Correct Answer is Right
The correct answer, **D. Increased inhibitory effect of oestrogen on gonadotropin secretion in females**, highlights a key factor. However, it seems there might have been a mix-up in the options provided. Typically, the explanation for the earlier onset of puberty in females compared to males involves the role of sex steroids. In females, the inhibitory effect of estrogen on gonadotropin secretion is less pronounced initially, allowing for an earlier increase in gonadotropins and onset of puberty. Conversely, in males, the increase in testosterone levels is more gradual, and there's a higher level of estrogen (produced from testosterone) which has a feedback inhibition on gonadotropin release, but this doesn't fully explain the delay without considering the overall effect of sex steroids on the HPG axis.

## Why Each Wrong Option is Incorrect
- **Option A:** This option is not provided, but typically, incorrect options might relate to other factors such as genetic differences, nutritional factors, or other hormonal influences not directly related to the sex-specific effects of estrogen and testosterone on the HPG axis.
- **Option B:** Similarly, without the content, it's hard to assess, but if it doesn't directly relate to the differential effects of sex steroids on gonadotropin secretion or HPG axis maturation, it would be incorrect.
- **Option C:** Again, without specifics, if this option does not accurately reflect the known physiological differences that lead to the earlier onset of puberty in females (such as the role of estrogen), it would be considered incorrect.

## Clinical Pearl / High-Yield Fact
A key point to remember is that the onset of puberty is heritable, with daughters of early-maturing mothers tending to enter puberty earlier themselves. This suggests a strong genetic component to the timing of puberty. Clinically, understanding the typical ages of puberty onset (usually 9-14 in boys and 8-13 in girls) helps in identifying precocious puberty (early onset) or delayed puberty.

## Correct Answer Line
**Correct Answer: D. Increased inhibitory effect of oestrogen on gonadotropin secretion in females.**