According to 'Rivet Popper hypothesis' , the popping of rivets means :

Options

A. Origin of species
B. Extinction of species
C. Environmental factors
D. Replacement of one species by another

Answer

### Step-by-Step Solution:

1. **Understanding the Rivet Popper Hypothesis**:
- The Rivet Popper Hypothesis was proposed by Paul Ehrlich. It uses the analogy of an airplane held together by rivets to explain the importance of species in an ecosystem.

2. **Analogy of the Airplane**:
- In this analogy, the airplane represents an ecosystem, and the rivets represent different species within that ecosystem. Just like rivets hold the airplane together, species contribute to the stability and functioning of an ecosystem.

3. **Popping of Rivets**:
- The "popping" of rivets refers to the extinction of species. Initially, removing a few rivets (or species) may not seem to affect the airplane's (or ecosystem's) functioning significantly.

4. **Consequences of Extinction**:
- However, as more rivets (species) are removed, the airplane (ecosystem) becomes weaker and more vulnerable. If critical rivets (key species) are removed, it can lead to catastrophic failure of the airplane (collapse of the ecosystem).

5. **Conclusion**:
- Therefore, according to the Rivet Popper Hypothesis, the popping of rivets signifies the extinction of species, which ultimately threatens the stability and productivity of the ecosystem.

6. **Final Answer**:
- The correct answer to the question is **B, extension of species**.