Which of the following diseases in plants is different from the others ?

Options

A. Mosaic formation
B. Leaf rolling and curling
C. Yellowing and in clearing
D. Potato spindle tuber disease

Answer

To determine which plant disease is different from the others, we will analyze the options provided and identify the causative agents of each disease.

### Step-by-Step Solution:

1. **Identify the Diseases:**
- **Option 1:** Mosaic formation
- **Option 2:** Leaf rolling and curling
- **Option 3:** Yellowing and vein clearing
- **Option 4:** Potato spindle tuber disease

2. **Causative Agents:**
- **Mosaic formation, Leaf rolling and curling, Yellowing and vein clearing:** These symptoms are typically associated with diseases caused by the **Tobacco Mosaic Virus (TMV)**. TMV is a viral pathogen that affects many plants, leading to the symptoms mentioned.
- **Potato spindle tuber disease:** This disease is caused by a **viroid**, which is a smaller infectious agent than a virus and consists solely of a short strand of RNA without a protein coat.

3. **Comparison:**
- The first three options (mosaic formation, leaf rolling and curling, yellowing and vein clearing) are all viral diseases caused by TMV.
- The fourth option (potato spindle tuber disease) is caused by a viroid, which is fundamentally different from a virus.

4. **Conclusion:**
- The disease that is different from the others is **Potato spindle tuber disease** (Option 4), as it is caused by a viroid while the others are caused by a virus.

### Final Answer:
The correct option is **Option 4: Potato spindle tuber disease**.

---