Trichocyst takes part in

Options

A. Defence
B. Reproduction
C. Nutrition
D. Osmoregulation.

Answer

**Step-by-Step Solution:**

1. **Understanding Trichocysts**: Trichocysts are specialized structures found in certain unicellular organisms, particularly in some protozoans. They are bottle-shaped and are located on the pellicle (outer membrane) of these organisms.

2. **Function of Trichocysts**: The primary function of trichocysts is to provide a defense mechanism. When an organism encounters a threat or stimulus that could potentially harm it, the trichocysts respond to this danger.

3. **Mechanism of Action**: Upon receiving a signal indicating danger, the trichocysts are extruded from the organism's body. This extrusion releases a substance that can deter predators or harmful stimuli, thus acting as a defense mechanism.

4. **Analyzing the Options**: Given the options:
- A) Defense
- B) Reproduction
- C) Nutrition
- D) Osmoregulation

Based on the function of trichocysts, we can eliminate options B (Reproduction), C (Nutrition), and D (Osmoregulation) as they do not relate to the role of trichocysts.

5. **Conclusion**: The correct answer is A) Defense, as trichocysts are primarily involved in protecting the organism from threats.