Clubroot is a

Options

A. Moss
B. Disease
C. Medicinal plant
D. Coral.

Answer

**Step-by-Step Solution:**

1. **Identify the Question**: The question asks what clubroot is, providing four options: moss, disease, medicinal plant, and coral.

2. **Understand the Term 'Clubroot'**: Clubroot is a term that refers to a specific condition affecting certain plants, particularly those in the Brassica family.

3. **Recognize the Affected Family**: Clubroot primarily affects plants in the Brassicaceae family, which includes common vegetables such as cabbage, broccoli, cauliflower, Brussels sprouts, and radishes.

4. **Identify the Cause**: The disease is caused by a soil-borne fungus known as *Plasmodiophora brassicae*. This fungus infects the roots of the plants.

5. **Describe the Symptoms**: The symptoms of clubroot include swollen roots that become deformed and take on a club-like shape. This deformation can lead to cracking of the roots.

6. **Explain the Impact on Plants**: Due to the swelling and deformation of the roots, the affected plants have difficulty absorbing water and nutrients, which can severely affect their overall health and growth.

7. **Evaluate the Options**:
- Moss: Incorrect, as moss is a type of plant.
- Disease: Correct, as clubroot is a disease.
- Medicinal plant: Incorrect, as clubroot does not refer to a plant with medicinal properties.
- Coral: Incorrect, as coral refers to marine invertebrates.

8. **Conclusion**: The correct answer to the question is that clubroot is a disease.

**Final Answer**: Clubroot is a disease.

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