Which one the following is a true nut

Options

A. Walnut
B. Cashewnut
C. Groundnut
D. Pistachio

Answer

### Step-by-Step Solution

1. **Understanding the Definition of a True Nut**:
- A true nut is a type of fruit that is hard and indehiscent, meaning it does not split open to release its seeds when mature. It is formed from a single ovary and typically has a hard outer shell.

2. **Identifying Key Characteristics of True Nuts**:
- True nuts are derived from a polycarpillary ovary, meaning they are formed from multiple carpels.
- They have a superior ovary, which means the ovary is positioned above the other floral parts (like petals and sepals).
- The pericarp (the fruit wall) of a true nut is hard or woody, and in some cases, leathery.
- The edible part of a true nut is the cotyledon.

3. **Analyzing the Options**:
- **Cashew Nut**: It meets all the criteria for a true nut. It has a polycarpillary structure, a superior ovary, a hard pericarp, and the edible part is the cotyledon.
- **Walnut**: This is classified as a drupe, not a true nut.
- **Pistachio**: Similar to walnut, it is also classified as a drupe.
- **Groundnut**: This is a legume and not a true nut.

4. **Conclusion**:
- Based on the characteristics and definitions discussed, the correct answer to the question "Which one of the following is a true nut?" is **Cashew Nut**.