Which of the following hormones is necessary for the development of secondary sexual characters in human beings?

Options

A. Estrogen
B. FSH
C. Testosterone
D. Both a and c

Explanation

To determine which hormones are necessary for the development of secondary sexual characters in human beings, let's analyze the options provided:

1. **Understanding Secondary Sexual Characteristics**:
- Secondary sexual characteristics are features that appear during puberty and differentiate the sexes but are not directly involved in reproduction. In males, these include features like facial hair, deeper voice, and increased muscle mass. In females, these include breast development, wider hips, and menstrual cycle regulation.

2. **Identifying the Hormones**:
- **Estrogen**: This hormone is primarily produced in the ovaries and is responsible for the development of female secondary sexual characteristics. It plays a crucial role during puberty in females.
- **Testosterone**: This hormone is produced in the testes and is responsible for the development of male secondary sexual characteristics. It also plays a significant role during puberty in males.
- **FSH (Follicle Stimulating Hormone)**: This hormone is involved in the development of ovarian follicles in females and is important for reproduction but does not directly influence the development of secondary sexual characteristics.

3. **Analyzing the Options**:
- The question asks for the hormones necessary for the development of secondary sexual characters.
- Since both Estrogen (for females) and Testosterone (for males) are responsible for these developments, they are the correct answers.
- FSH, while important for reproductive processes, does not contribute to the secondary sexual characteristics.

4. **Conclusion**:
- The correct answer is **both A (Estrogen) and C (Testosterone)**, which corresponds to option 4.

### Final Answer:
The hormones necessary for the development of secondary sexual characters in human beings are **both Estrogen and Testosterone** (Option 4).