Menstrual cycle is characteristic to
1. Most seasonal breeders
2. Human females
3. Old world monkeys and apes
4. Cows

Options

A. 2,3,4
B. 2,3
C. 3,4
D. 1,2

Answer

To determine which option correctly identifies the characteristic of the menstrual cycle, we can analyze each option step by step.

1. **Understanding the Menstrual Cycle**: The menstrual cycle is a series of natural changes in hormone production and the structures of the uterus and ovaries of female primates. It is a key reproductive process.

2. **Evaluating Option 1: Most Seasonal Breeders**: Seasonal breeders typically have reproductive cycles that are influenced by environmental factors such as seasons. They do not have a menstrual cycle; instead, they may have estrous cycles. Therefore, this option is incorrect.

3. **Evaluating Option 2: Human Females**: The menstrual cycle is indeed a characteristic feature of human females. It involves a regular cycle of ovulation and menstruation. Therefore, this option is correct.

4. **Evaluating Option 3: Old World Monkeys and Apes**: Similar to human females, Old World monkeys and apes also experience a menstrual cycle. This is a characteristic feature of these primates. Therefore, this option is also correct.

5. **Evaluating Option 4: Cows**: Cows do not have a menstrual cycle; they have an estrous cycle, which is different from the menstrual cycle. Therefore, this option is incorrect.

**Conclusion**: The menstrual cycle is characteristic of both human females (Option 2) and Old World monkeys and apes (Option 3). However, since the question asks for a singular characteristic, the most direct answer is Option 2: Human females.

### Final Answer:
**Option 2: Human females**