In which of the following systeam primitives `a != b != c`?

Options

A. Orthorhombic
B. Monoclinic
C. Triclinic
D. Hexagonal

Answer

To solve the question regarding which crystal system has the condition \( a \neq b \neq c \), we will analyze the properties of the seven crystal systems.

### Step-by-Step Solution:

1. **Understanding Crystal Systems**:
- There are seven crystal systems: Cubic, Tetragonal, Orthorhombic, Hexagonal, Rhombohedral, Monoclinic, and Triclinic.
- Each system has specific relationships between the lengths of its edges (a, b, c) and the angles between them.

2. **Identifying Edge Relationships**:
- **Cubic**: \( a = b = c \)
- **Tetragonal**: \( a = b \neq c \)
- **Orthorhombic**: \( a \neq b \neq c \)
- **Hexagonal**: \( a = b \neq c \)
- **Rhombohedral**: \( a = b = c \)
- **Monoclinic**: \( a \neq b \neq c \) (but angles are not all equal)
- **Triclinic**: \( a \neq b \neq c \) (and angles are not equal)

3. **Analyzing the Conditions**:
- We are looking for a system where all three edges (a, b, c) are unequal.
- From the analysis, we find that:
- **Orthorhombic** is the primary system where \( a \neq b \neq c \) and all angles are equal.
- **Monoclinic** and **Triclinic** also have \( a \neq b \neq c \), but their angles are not equal.

4. **Conclusion**:
- The crystal system that satisfies the condition \( a \neq b \neq c \) is **Orthorhombic**.

### Final Answer:
The answer is **Orthorhombic**.