In ' Rivet popper hypothesis', rivets of wings are considered as

Options

A. Dominant species
B. Critical link species
C. Rare species
D. Keystone species

Answer

### Step-by-Step Solution:

1. **Understanding the Rivet Popper Hypothesis**: The Rivet Popper Hypothesis was proposed by Paul Ehrlich. It emphasizes the importance of species richness in maintaining the stability and functionality of ecosystems. The analogy used is that species in an ecosystem are like rivets in an airplane wing; if too many rivets (species) are lost, the wing (ecosystem) may fail.

2. **Analyzing the Options**:
- **Option 1: Dominant Species**: Dominant species are those that have a high abundance relative to other species in a community. This option does not align with the concept of rivets in the hypothesis.
- **Option 2: Critical Link Species**: Critical link species play an important role in maintaining the structure of the ecosystem. However, this term does not specifically relate to the rivet analogy.
- **Option 3: Rare Species**: Rare species are defined as those with small populations. This does not fit the description of rivets in the context of the hypothesis.
- **Option 4: Keystone Species**: Keystone species are those that have a disproportionately large effect on their environment relative to their abundance. This is the correct analogy for rivets in the Rivet Popper Hypothesis, as the loss of keystone species can lead to significant changes in the ecosystem.

3. **Conclusion**: The rivets of wings in the Rivet Popper Hypothesis are considered as **Keystone Species**. Therefore, the correct answer is option 4.