Match the following
`{:("(a) Potato spindle", "(i) Virus"),("(b) Cr-Jacob disease (CJD)", "(ii) Viroid"),("(c) Cholera" ,"(iii) Prion"),("(d) Leaf rolling and curling", "(iv) Bacteria"):}`

Options

A. a – i, b–ii, c–iii, d –iv
B. a – iv, b–iii, c–ii, d –i
C. a – ii, b–iii, c–iv, d –i
D. a – iv, b–i, c–iii, d –ii

Answer

To solve the matching question, we need to identify the correct associations between the diseases and their respective causative agents. Let's break it down step by step.

### Step-by-Step Solution:

1. **Identify the Causative Agent for Each Disease:**
- **(a) Potato spindle**: This disease is caused by a viroid, specifically the potato spindle tuber viroid.
- **(b) C. R. Jacob disease (CJD)**: This is a degenerative brain disorder caused by prions, which are misfolded proteins.
- **(c) Cholera**: This disease is caused by bacteria, specifically the bacterium Vibrio cholerae.
- **(d) Leaf rolling and curling**: This condition is caused by a virus, such as the chili leaf curl virus.

2. **Match Each Disease with Its Causative Agent:**
- **(a) Potato spindle** → **(ii) Viroid**
- **(b) C. R. Jacob disease (CJD)** → **(iii) Prion**
- **(c) Cholera** → **(iv) Bacteria**
- **(d) Leaf rolling and curling** → **(i) Virus**

3. **Compile the Matches:**
- A → ii
- B → iii
- C → iv
- D → i

4. **Convert Matches to Numerical Codes:**
- A = 2 (Viroid)
- B = 3 (Prion)
- C = 4 (Bacteria)
- D = 1 (Virus)

5. **Final Matching Code:**
- The final matching code is: **2, 3, 4, 1**.

6. **Select the Correct Option:**
- The correct option that corresponds to the matching code **2, 3, 4, 1** is option **3**.

### Conclusion:
The answer to the matching question is option **3**: **2, 3, 4, 1**.