Read the following statements and select the option which identifies the incorrect ones.
(i) Potato spindle tuber disease and Chrysanthermum stunt disease are caused by viroids.
(ii) `T_(4)` bacteriophage exhibits lytic cycle.
(iii) Retroviruses have two copies of ssRNA.
(iv) Interferous which prevent viral multiplication are glycolipid particles.

Options

A. ii and iii
B. i and iv
C. iii only
D. iv only

Explanation

To identify the incorrect statement from the given options, we will analyze each statement one by one.

### Step 1: Analyze the first statement
**Statement (i):** Potato spindle tuber disease and Chrysanthemum stunt disease are caused by viroids.

- **Explanation:** Viroids are indeed known to cause diseases in plants, including potato spindle tuber disease and chrysanthemum stunt disease. This statement is **true**.

### Step 2: Analyze the second statement
**Statement (ii):** T4 bacteriophage exhibits lytic cycle.

- **Explanation:** T4 bacteriophage is a well-known bacteriophage that primarily exhibits the lytic cycle, where it infects a bacterial cell, replicates, and ultimately causes the cell to lyse (burst). This statement is **true**.

### Step 3: Analyze the third statement
**Statement (iii):** Retroviruses have two copies of ssRNA.

- **Explanation:** Retroviruses, such as HIV, contain two identical single-stranded RNA (ssRNA) molecules. This statement is **true**.

### Step 4: Analyze the fourth statement
**Statement (iv):** Interferons which prevent viral multiplication are glycolipid particles.

- **Explanation:** Interferons are actually proteins that are produced by host cells in response to viral infections. They help to inhibit viral replication in neighboring cells. They are not glycolipid particles; hence this statement is **false**.

### Conclusion
The incorrect statement is **(iv)**: Interferons which prevent viral multiplication are glycolipid particles.

### Final Answer
The incorrect statement is: **(iv) Interferons which prevent viral multiplication are glycolipid particles.**

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