Facultative parasites are those which are ?

Options

A. Strictly parasites
B. Usually saprophytes but can also live as parasites
C. Usually parasites but can also lives a saprophytes
D. Strictly saprophytes

Answer

### Step-by-Step Solution:

1. **Understanding the Terms**:
- First, we need to understand what a parasite is. A parasite is an organism that lives in or on a host and derives nutrients at the host's expense.
- Next, we need to clarify the term "facultative." This means that an organism can switch between different modes of nutrition or living conditions.

2. **Defining Facultative Parasites**:
- Facultative parasites are organisms that are primarily saprophytes, meaning they usually feed on dead and decaying organic matter. However, they have the ability to switch to a parasitic mode of life when a suitable host is available.

3. **Comparison with Other Types of Parasites**:
- Unlike obligate parasites, which must live on a host to survive, facultative parasites do not depend entirely on their host for their life cycle. They can thrive independently as saprophytes.

4. **Conclusion**:
- Therefore, facultative parasites are best described as organisms that are usually saprophytes but can also live as parasites when conditions allow. This means they have a flexible mode of nutrition.

5. **Final Answer**:
- The correct statement about facultative parasites is that they are usually saprophytes but can also live as parasites.