The smallest free living organism is

Options

A. Virus
B. Viroid
C. Mycoplasma
D. Prions

Answer

To determine the smallest free-living organism, we can analyze the options provided in the question step by step.

### Step 1: Analyze the Options
1. **Virus**: Viruses are not considered living organisms when they are outside a host. They require a host cell to replicate and carry out metabolic processes.

**Hint**: Remember that viruses cannot survive independently.

2. **Viroid**: Viroids are small, circular pieces of RNA that can infect plants. However, they are not classified as living organisms because they lack the cellular structure and do not have the machinery to replicate on their own.

**Hint**: Consider the definition of living organisms and the characteristics they must have.

3. **Mycoplasma**: Mycoplasma are the smallest known free-living organisms. They lack a cell wall and can survive independently. They are capable of reproduction and can be pathogenic to both plants and animals.

**Hint**: Look for organisms that can live independently and reproduce.

4. **Prion**: Prions are infectious agents composed of protein and lack nucleic acids. They are associated with certain diseases but do not fit the criteria for living organisms.

**Hint**: Think about the structural components that define living organisms.

### Step 2: Conclusion
Based on the analysis, the smallest free-living organism is **Mycoplasma**. It is the only option that meets the criteria of being a living organism capable of independent survival.

### Final Answer
The smallest free-living organism is **Mycoplasma**.