Which is not a true organelle?

Options

A. Lysosome
B. Mitochondria
C. Ribosomes
D. Chloroplast

Explanation

**Step-by-Step Solution:**

1. **Understand the Definition of True Organelles**: True organelles are defined as cell components that are membrane-bound and can carry out specific functions even when isolated from the cell, provided the right environment is present.

2. **Identify the Options**: The options given are lysosome, mitochondria, and ribosome.

3. **Analyze Each Option**:
- **Lysosome**: This is a membrane-bound organelle that contains digestive enzymes to break down waste materials and cellular debris. It is a true organelle.
- **Mitochondria**: Known as the powerhouse of the cell, mitochondria are also membrane-bound organelles responsible for energy production through cellular respiration. This is a true organelle.
- **Ribosome**: Ribosomes are not membrane-bound structures. They are made up of ribonucleic acid (RNA) and proteins and are involved in protein synthesis. Therefore, ribosomes do not qualify as true organelles.

4. **Conclusion**: Since ribosomes are not membrane-bound and are classified as macromolecules rather than true organelles, the answer to the question "Which is not a true organelle?" is ribosome.

**Final Answer**: Ribosome is not a true organelle.

---