Estradiol hormone is responsible for:

Secondary female characters

The correct answer is option 3. Secondary female characters.

Estradiol, a key estrogen hormone, plays a significant role in various physiological processes. Here's a detailed look at its functions:

Let us now look at the given options:

1. Relief from Stress:

Estradiol is not primarily responsible for stress relief. While hormonal fluctuations can influence mood and stress responses, estradiol's main roles are more specific to reproductive health and secondary sexual characteristics.

2. Lethargy and Obesity:

Estradiol is not directly responsible for lethargy and obesity. However, imbalances in estrogen levels can influence body weight and energy levels, particularly during menopause or hormonal disorders.

3. Secondary Female Characteristics:

Estradiol is primarily responsible for the development and maintenance of secondary female sexual characteristics. These include the development of breasts, wider hips, and the regulation of the menstrual cycle. Estradiol is crucial for the differentiation and maturation of female reproductive organs and the expression of secondary sexual traits.

4. Balance Glucose Levels:

While estradiol does have some influence on glucose metabolism and insulin sensitivity, its primary role is not in directly balancing glucose levels. Other hormones, like insulin and glucagon, are more directly involved in glucose regulation.

Conclusion: Estradiol's main role is in the development and maintenance of secondary female sexual characteristics.

Therefore, the correct answer is: 3. Secondary female characteristics.