Which of the following lacks a nucleus on maturity ?

Options

A. Companion cells
B. Sieve tube elements
C. Phloem parenchyma
D. None of the above

Answer

To solve the question "Which of the following lacks a nucleus on maturity?" we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks which cell type lacks a nucleus when it reaches maturity. We need to analyze the options provided.

2. **Identify the Options**: The options given are:
- Companion cells
- Sieve tube elements
- Phloem parenchyma
- None of the above

3. **Analyze Each Option**:
- **Companion Cells**: These cells are associated with sieve tubes and have a prominent nucleus at maturity. Therefore, they do not lack a nucleus.
- **Sieve Tube Elements**: These are elongated cells that form the sieve tubes in the phloem. At maturity, they lack a nucleus but contain some organelles. This makes them a strong candidate for the answer.
- **Phloem Parenchyma**: These cells are involved in the storage of food and have a nucleus at maturity. Hence, they do not fit the criteria.
- **None of the Above**: This option implies that all the previous options have a nucleus at maturity, which is incorrect based on our analysis.

4. **Conclusion**: Based on the analysis, the only option that lacks a nucleus at maturity is the **Sieve Tube Elements**.

5. **Final Answer**: The correct answer is **Sieve Tube Elements**.