Which of the following secretes the hormone responsible for relaxing pubic symphysis during the childbirth ?

Options

A. Pineal gland
B. Macula
C. Corpus albicans
D. Placenta

Answer

To solve the question, "Which of the following secretes the hormone responsible for relaxing pubic symphysis during childbirth?", we will analyze the options provided and identify the correct answer step by step.

### Step-by-Step Solution:

1. **Identify the Hormone**: The hormone responsible for relaxing the pubic symphysis during childbirth is known as relaxin. This hormone plays a crucial role in preparing the body for labor by relaxing the ligaments and softening the cervix.

2. **Evaluate Each Option**:
- **Option 1: Pineal Gland**: The pineal gland is primarily responsible for the secretion of melatonin, which regulates sleep-wake cycles. It does not secrete relaxin, so this option is incorrect.
- **Option 2: Macula**: The macula is a part of the retina in the eye and is involved in vision. It does not produce any hormones related to childbirth, making this option incorrect as well.
- **Option 3: Corpus Albicans**: The corpus albicans is a structure formed from the degenerated corpus luteum after ovulation. It does not secrete relaxin, thus this option is also incorrect.
- **Option 4: Placenta**: The placenta is an organ that develops during pregnancy and is responsible for various functions, including hormone secretion. It secretes relaxin, which helps in relaxing the ligaments of the pelvis and widening the cervix during childbirth.

3. **Conclusion**: After evaluating all the options, the correct answer is **Option 4: Placenta**, as it is the only structure that secretes the hormone relaxin, which is responsible for relaxing the pubic symphysis during childbirth.

### Final Answer:
**Option 4: Placenta**