Eutherians are characterized by

Options

A. Skin with glands
B. Hairy skin
C. True placentation
D. Locomotary hind-limbs

Answer

**Step-by-Step Solution:**

1. **Understanding Eutherians**: Eutherians are a group of mammals that are also known as true placental mammals. This classification is important as it distinguishes them from other types of mammals such as monotremes (egg-laying mammals) and marsupials (like kangaroos).

2. **Characteristics of Eutherians**: The defining characteristic of eutherians is the presence of a well-developed placenta. This placenta allows for a more efficient transfer of nutrients and oxygen from the mother to the developing offspring during gestation.

3. **Comparison with Other Mammals**:
- **Protherians**: These are egg-laying mammals (like the platypus) that do not have a placenta.
- **Metatherians**: These include marsupials (like kangaroos) that have a less developed placenta and give birth to underdeveloped young that continue to develop in a pouch.

4. **Significance of True Placentation**: The true placenta in eutherians supports longer gestation periods, allowing the offspring to be more developed at birth compared to those of metatherians and protherians.

5. **Conclusion**: Therefore, the main characteristic that defines eutherians is true placentation, which is essential for the development of their young.

**Final Answer**: Eutherians are characterized by true placentation.

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