Mammals evolved from:

Options

A. Birds
B. Reptiles
C. Amphibians
D. None of these

Explanation

**Step-by-Step Solution:**

1. **Understanding the Origin of Mammals**: Mammals are a distinct class of animals that have certain unique characteristics. To understand their evolution, we need to look at their ancestral lineage.

2. **Timeline of Evolution**: Mammals first appeared on Earth approximately 250 million years ago. This timeline is crucial as it helps us place mammals within the broader context of evolutionary history.

3. **Fossil Evidence**: Fossils provide critical evidence for understanding the evolutionary connections between different groups of organisms. One notable fossil example is the duck-billed platypus, which exhibits characteristics of both mammals and reptiles.

4. **Connecting Links**: The term "connecting link" refers to organisms that show traits of two different taxonomic groups. The duck-billed platypus is an example because it has features common to both mammals (like mammary glands and hairy skin) and reptiles (like the presence of a cloaca).

5. **Characteristics of Reptiles and Mammals**: Mammals evolved from reptiles, as evidenced by certain shared characteristics. For instance, the presence of a cloaca in both groups indicates a common ancestry. Additionally, the evolution of mammary glands and fur in mammals marks a significant divergence from their reptilian ancestors.

6. **Conclusion**: Based on the fossil evidence and shared characteristics, scientists conclude that mammals evolved from reptiles. This makes reptiles the correct answer to the question of the origin of mammals.

**Final Answer**: Mammals evolved from reptiles.

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