The sex hormone which controls the development and maintenance of pregnancy is

Options

A. Cortisone
B. Thyroxine
C. Progesterone
D. Estrone

Answer

To answer the question regarding the sex hormone that controls the development and maintenance of pregnancy, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Options**: The question provides four options:
- Option 1: Cortisone
- Option 2: Thyroxine
- Option 3: Progesterone
- Option 4: Esterone

2. **Understand the Role of Hormones in Pregnancy**:
- Hormones are crucial for regulating various physiological processes, including the menstrual cycle and pregnancy.
- During pregnancy, specific hormones are responsible for maintaining the pregnancy and supporting fetal development.

3. **Evaluate Each Option**:
- **Cortisone**: This is a steroid hormone involved in stress response and metabolism but does not play a direct role in pregnancy maintenance.
- **Thyroxine**: This hormone is produced by the thyroid gland and regulates metabolism but is not primarily involved in pregnancy maintenance.
- **Progesterone**: This hormone is produced in the ovaries and later in the placenta during pregnancy. It plays a significant role in preparing the body for conception and maintaining pregnancy.
- **Esterone**: This is an estrogen hormone but does not specifically control pregnancy maintenance.

4. **Confirm the Role of Progesterone**:
- Progesterone prepares the uterus for implantation of the fertilized egg and helps maintain the uterine lining throughout pregnancy.
- It regulates the menstrual cycle and prevents ovulation during pregnancy.
- Progesterone levels remain elevated during pregnancy, which is crucial for the development of the fetus.

5. **Conclusion**: Based on the evaluation of the options and understanding the role of progesterone, we conclude that the sex hormone which controls the development and maintenance of pregnancy is **Progesterone** (Option 3).

### Final Answer:
The sex hormone which controls the development and maintenance of pregnancy is **Progesterone**.

---