Lila observed that a pond with clear water was covered up with a green algae within a week. By which method of reproduction did the algae spread so rapidly ?

Options

A. Budding
B. Sexual reproduction
C. Fragmentation
D. Pollination

Answer

### Step-by-Step Solution:

1. **Observation of the Pond**:
- Lila noticed that a pond that was initially clear became covered with green algae within a week.

2. **Understanding Reproduction**:
- To determine how the algae spread so rapidly, we need to understand the methods of reproduction in algae. There are two main types: asexual reproduction and sexual reproduction.

3. **Identifying the Type of Reproduction**:
- Asexual reproduction does not involve gametes (sperm and egg), while sexual reproduction does. Since the algae covered the pond quickly, it suggests a method that allows for rapid population increase.

4. **Fragmentation as a Method**:
- Algae primarily reproduce asexually through a process called fragmentation. In fragmentation, the algae body breaks into smaller pieces (fragments), and each piece can grow into a new individual.

5. **Rapid Growth**:
- Because each fragment can develop into a new algae, this process can lead to a large number of algae in a short time, explaining why the pond was covered so quickly.

6. **Conclusion**:
- Therefore, the method of reproduction that allowed the algae to spread rapidly in the pond is **fragmentation**.

### Final Answer:
The algae spread rapidly by the method of reproduction called **fragmentation**.

---