A. During fertilization, a sperm comes in contact with the.zona pellucida layer and induces the changes in the membrane that block the entry of additional sperm.
B. The milk produced during initial few days of lactation is called Colostrum having antibodies.
C. In human beings, menstrual cycle ceases around 50 years of age. it is called menopause.
D. After one month of pregnancy major organ system are formed.

Options

A. All are correct
B. All are incorrect
C. D is correct
D. All correct except D

Answer

To analyze the statements provided in the question, we will evaluate each statement step by step.

### Step-by-Step Solution:

1. **Statement A**: "During fertilization, a sperm comes in contact with the zona pellucida layer and induces the changes in the membrane that block the entry of additional sperm."
- **Analysis**: This statement is correct. The zona pellucida is a glycoprotein layer surrounding the oocyte. When a sperm penetrates this layer, it triggers a reaction that prevents other sperm from entering, known as the block to polyspermy. Thus, this statement is true.

2. **Statement B**: "The milk produced during initial few days of lactation is called Colostrum having antibodies."
- **Analysis**: This statement is also correct. Colostrum is the first milk produced by the mother after childbirth, rich in antibodies, particularly immunoglobulin A (IgA), which helps protect the newborn. Therefore, this statement is true.

3. **Statement C**: "In human beings, menstrual cycle ceases around 50 years of age. it is called menopause."
- **Analysis**: This statement is correct as well. Menopause typically occurs around the age of 50 in women, marking the end of the menstrual cycle and reproductive years. Thus, this statement is true.

4. **Statement D**: "After one month of pregnancy major organ systems are formed."
- **Analysis**: This statement is incorrect. While some development occurs in the first month, major organ systems are not fully formed until later in pregnancy. The heart is one of the first organs to develop, but the complete organ systems take longer to form. Therefore, this statement is false.

### Conclusion:
- Statements A, B, and C are correct.
- Statement D is incorrect.

The correct answer is that all statements are correct except for statement D.