Appearance of ancestral characters in the new borns, such as tail, gill slits, etc. are known as

Options

A. Homologous
B. Analogous
C. Vestigial
D. Atavism

Answer

To solve the question regarding the appearance of ancestral characters in newborns, such as tails and gill slits, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about the phenomenon where ancestral traits reappear in newborns. Examples given include tails and gill slits.

2. **Identifying Key Terms**:
- Ancestral characters: Traits that were present in ancestors but may have disappeared in later generations.
- Newborns: The offspring in which these traits are observed.

3. **Analyzing the Options**:
- **Homologous**: Refers to organs that have a common evolutionary origin but may serve different functions in different species. This does not fit the description of reappearing ancestral traits.
- **Analogous**: Refers to organs that serve similar functions but do not share a common evolutionary origin. This also does not describe the reappearance of ancestral traits.
- **Vestigial**: Refers to organs that were functional in ancestors but have lost their original function in later generations. While this relates to ancestral traits, it does not specifically refer to their reappearance in newborns.
- **Atavism**: This term specifically refers to the reappearance of ancestral traits that had disappeared in previous generations. This is the correct term for the phenomenon described in the question.

4. **Conclusion**: Based on the analysis, the correct answer is **Atavism**. This term accurately describes the reappearance of ancestral characters such as tails and gill slits in newborns.

### Final Answer:
The appearance of ancestral characters in newborns, such as tails and gill slits, is known as **Atavism**.

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