Breast development during pregnancy is induced by

Options

A. Estradiol
B. Progesterone
C. Relaxin
D. None of the above

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the hormone responsible for breast development during pregnancy.

2. **Identifying Key Hormones**: The hormones mentioned are estradiol, progesterone, and relaxin. We need to analyze each of these hormones to determine which one is primarily responsible for breast development during pregnancy.

3. **Role of Estradiol**: Estradiol is a form of estrogen that plays a crucial role in maintaining the female reproductive system. While it is important for overall reproductive health, it is not the primary hormone responsible for breast development during pregnancy.

4. **Role of Progesterone**: Progesterone is secreted by the corpus luteum and is known for its role in preparing the mammary glands for milk secretion. It is crucial for breast development during pregnancy as it helps in the growth and differentiation of breast tissue.

5. **Role of Relaxin**: Relaxin is primarily involved in cervical ripening and does not play a direct role in breast development. Its main function is to prepare the body for childbirth.

6. **Conclusion**: Based on the analysis of the functions of these hormones, the correct answer to the question is that breast development during pregnancy is induced by **progesterone**.

**Final Answer**: Breast development during pregnancy is induced by **progesterone**.

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