Forelimbs of humans and wings of birds are

Options

A. Analogous organs
B. Homologous organs
C. Parallel organs
D. Vestigial organs.

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about the relationship between the forelimbs of humans and the wings of birds. We need to classify these structures based on their anatomical and functional characteristics.

2. **Defining Key Terms**:
- **Homologous Organs**: These are organs that have a similar structure and developmental origin but may serve different functions. They indicate a common ancestry.
- **Analogous Organs**: These are organs that have different structures but perform similar functions. They do not share a common ancestry.
- **Vestigial Organs**: These are organs that have lost their original function through evolution.
- **Parallel Organs**: These are not a standard classification in evolutionary biology.

3. **Analyzing the Forelimbs of Humans and Wings of Birds**:
- Both the forelimbs of humans and the wings of birds share a similar underlying structure (bones like humerus, radius, and ulna) and developmental origin, indicating that they evolved from a common ancestor.
- Despite their different functions (grasping in humans and flying in birds), their structural similarities classify them as homologous organs.

4. **Conclusion**: Based on the definitions and analysis, the forelimbs of humans and wings of birds are classified as **homologous organs**.

### Final Answer:
The forelimbs of humans and wings of birds are **homologous organs**.

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