Living mature cell which lacks nucleus is

Options

A. Xylem vessel
B. companion cells
C. Sieve cells
D. None of these

Answer

To solve the question "Living mature cell which lacks nucleus is," we will analyze the options provided one by one.

### Step-by-Step Solution:

1. **Understand the Question**: The question asks for a living mature cell that lacks a nucleus. This means we are looking for a specific type of cell in plants that is functional and does not contain a nucleus.

2. **Evaluate the Options**:
- **Option 1: Xylem Vessel**
- Xylem vessels are part of the xylem tissue, which is responsible for the conduction of water in plants. However, xylem vessels are composed of dead cells at maturity. Therefore, they cannot be the answer as they do not meet the criteria of being living cells.

- **Option 2: Companion Cell**
- Companion cells are found in the phloem tissue and are involved in the transport of nutrients. These cells are living and contain a nucleus. Since the question specifies that we need a cell that lacks a nucleus, companion cells cannot be the answer.

- **Option 3: Sieve Cell**
- Sieve cells are also part of the phloem tissue and are responsible for the transport of sugars and other organic nutrients. Sieve cells are living cells, but they are unique in that they lose their nucleus as they mature. Thus, they fit the criteria of being living mature cells that lack a nucleus.

- **Option 4: None of These**
- This option implies that none of the previous options are correct. However, since we have identified sieve cells as living mature cells that lack a nucleus, this option is incorrect.

3. **Conclusion**: Based on the evaluation of the options, the correct answer is **sieve cell**.

### Final Answer:
**Sieve Cell**