Assertion (A) : Triclinic systeam is the most unsymmetrical systeam.
Reason (R ) : No axial angle is equal to `90^(@)` in triclinic systeam.

Options

A. If both `(A)` and `(R)` are correct, and `(R)` is the correct explanation of `(A)`
B. If both `(A)` and `(R)` are correct, but `(R)` is not the correct explanation of `(A)`
C. If `(A)` is correct, but `(R)` is incorrect.
D. If both `(A)` is incorrect but `(R)` is correct.

Explanation

To solve the question, we need to analyze the assertion (A) and the reason (R) provided.

### Step 1: Understand the Assertion (A)
The assertion states that "Triclinic system is the most unsymmetrical system."

- In crystallography, the triclinic system is characterized by having no symmetry elements. This means that the lengths of the axes (a, b, c) are all different, and the angles between them (α, β, γ) are also different and not equal to 90 degrees.

### Step 2: Understand the Reason (R)
The reason states that "No axial angle is equal to 90 degrees in the triclinic system."

- This is true because, in a triclinic crystal system, all three axial angles (α, β, γ) are not equal to 90 degrees. This lack of right angles contributes to the unsymmetrical nature of the system.

### Step 3: Analyze the Relationship Between A and R
Now we need to determine if the reason (R) is the correct explanation for the assertion (A).

- While both the assertion and the reason are true, the reason does not fully explain why the triclinic system is the most unsymmetrical. The unsymmetrical nature is primarily due to the unequal lengths of the axes (a ≠ b ≠ c), not solely because the angles are not equal to 90 degrees.

### Conclusion
Based on the analysis:
- Assertion (A) is true.
- Reason (R) is true.
- However, R is not the correct explanation for A.

Thus, the correct answer is **Option B**: Both A and R are correct, but R is not the correct explanation of A.

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