"Curly top" of tobacco is caused by "A"and it spreads through a plant via "B". A and B are

Options

A. Bacteria and cell sap
B. Virus and Xylem
C. Fungi and Phloem
D. Virus and Phloem

Answer

To solve the question regarding the "Curly top" disease of tobacco, we need to identify the cause of the disease (A) and the method of its spread (B). Here’s a step-by-step breakdown:

### Step 1: Identify the Cause of "Curly Top" Disease
- The "Curly top" disease of tobacco is known to be caused by a specific type of virus. In this case, it is caused by **curtoviruses**.

### Step 2: Determine How the Disease Spreads
- The disease spreads through the plant via specific tissues. In the case of "Curly top," the virus spreads through the **phloem tissue**, which is responsible for the transport of nutrients and organic compounds in plants.

### Step 3: Combine the Findings
- Therefore, we can conclude that:
- A (the cause) is **virus** (specifically curtoviruses).
- B (the method of spread) is **phloem**.

### Final Answer
- A = virus
- B = phloem