Which one of the following statement is correct

Options

A. Prions are the smallest free living cells
B. The cell wall of mycoplasmas is made up of amino sugars
C. Viroids consist of single stranded RNA molecule
D. Rickettside lack cell wall

Explanation

To determine which statement is correct among the options provided, we will analyze each statement step by step.

### Step 1: Analyze the first statement about Pryons
- **Statement**: "Pryons are the smallest free-living cells."
- **Analysis**: Pryons are not cells; they are infectious proteins that can cause diseases. They do not have cellular structure and are not classified as living cells. Therefore, this statement is incorrect.

### Step 2: Analyze the second statement about Mycoplasmas
- **Statement**: "The cell wall of mycoplasmas is made up of amino sugars."
- **Analysis**: Mycoplasmas are unique because they lack a cell wall entirely. They are the smallest free-living cells but do not have a cell wall composed of amino sugars or any other material. Thus, this statement is also incorrect.

### Step 3: Analyze the third statement about Viroids
- **Statement**: "Viroids consist of single-stranded RNA molecules."
- **Analysis**: Viroids are indeed composed of naked, circular, single-stranded RNA molecules. They do not have a protein coat and are simpler than viruses. This statement is correct.

### Step 4: Analyze the fourth statement about the cell wall
- **Statement**: "Right side lacks cell wall."
- **Analysis**: This statement appears to be vague and does not provide enough context. However, if it refers to the fact that certain organisms, like mycoplasmas, lack a cell wall, it is not a clear or accurate statement. Therefore, this statement is likely incorrect.

### Conclusion
After analyzing all the statements, the correct statement is:
- **"Viroids consist of single-stranded RNA molecules."**

### Final Answer
The correct answer is the third statement about Viroids.

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