Which of the following secondary sexual characteristics is observed only in girls at the time of puberty?

Options

A. Development of testes
B. Development of breasts
C. Growth of hair in underarms
D. Growth of hair in the pubic area

Answer

To determine which secondary sexual characteristic is observed only in girls at the time of puberty, let's analyze the options provided step by step.

### Step-by-Step Solution:

1. **Understanding Secondary Sexual Characteristics**:
- These are features that develop during puberty and distinguish between the sexes but are not directly involved in reproduction.

2. **Analyzing the Options**:
- **Option 1: Development of Testes**:
- This characteristic is specific to males. The testes develop in boys during puberty and are responsible for producing testosterone.
- **Conclusion**: This option is incorrect for girls.

- **Option 2: Development of Breasts**:
- This characteristic is specific to females. During puberty, girls experience breast development due to the influence of hormones like estrogen and progesterone.
- **Conclusion**: This option is correct as it is observed only in girls.

- **Option 3: Growth of Hair in Underarms**:
- This characteristic occurs in both males and females during puberty. Therefore, it is not exclusive to girls.
- **Conclusion**: This option is incorrect.

- **Option 4: Growth of Hair in the Pubic Area**:
- Similar to underarm hair, this characteristic also occurs in both sexes during puberty.
- **Conclusion**: This option is incorrect.

3. **Final Answer**:
- Based on the analysis, the secondary sexual characteristic observed only in girls at the time of puberty is the **development of breasts** (Option 2).