Go through the following statement
(i) Relaxin produced by the ovary, facilitates delivery of the foetus by softening the connective tissue of pubic symphysis and relaxing the pelvic ligaments and joints.
(ii) By the end of fifth month of pregnancy, the foetus develops limbs and digits.
(iii) Thalidomide is a teratogenic drug which causes a condition called phocomelia.
(iv). Although the levels of prolactin are high during pregnancy, milk secretion does not occur because of the high oestrogen and progesterone levels which make the breast unresponsive to the prolactin.
Which of these are correct?

Options

A. `i`,ii and iii
B. `i`, iii and iv
C. ii, iii and iv
D. all are correct

Explanation

To determine which statements are correct regarding human reproduction, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement (i)**: "Relaxin produced by the ovary facilitates delivery of the foetus by softening the connective tissue of pubic symphysis and relaxing the pelvic ligaments and joints."
- **Analysis**: Relaxin is indeed produced by the ovaries and the placenta. Its primary role during pregnancy is to help in the delivery process by softening the connective tissues and relaxing the pelvic ligaments and joints.
- **Conclusion**: This statement is **correct**.

2. **Statement (ii)**: "By the end of the fifth month of pregnancy, the foetus develops limbs and digits."
- **Analysis**: Limb and digit development occurs much earlier in pregnancy, typically starting in the second month (around 6-8 weeks). By the end of the fifth month, the limbs and digits are already well-developed.
- **Conclusion**: This statement is **incorrect**.

3. **Statement (iii)**: "Thalidomide is a teratogenic drug which causes a condition called phocomelia."
- **Analysis**: Thalidomide is known to be a teratogenic drug that can cause severe birth defects, including phocomelia, which is characterized by limb malformations. This condition arises when the drug is taken during pregnancy.
- **Conclusion**: This statement is **correct**.

4. **Statement (iv)**: "Although the levels of prolactin are high during pregnancy, milk secretion does not occur because of the high oestrogen and progesterone levels which make the breast unresponsive to the prolactin."
- **Analysis**: During pregnancy, high levels of estrogen and progesterone indeed prevent milk secretion despite high prolactin levels. This is a well-documented physiological response.
- **Conclusion**: This statement is **correct**.

### Final Conclusion:
The correct statements are (i), (iii), and (iv). Therefore, the answer is that statements 1, 3, and 4 are correct.