Assertion (A): Barium is not required for normal biological function in human beings.
Reason (R ): Barium does not show variable oxidation states.

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 `(A)` is incrrect, but `(R )` is correct.

Explanation

To solve the assertion-reason question, we will analyze both the assertion (A) and the reason (R) step by step.

### Step 1: Analyze the Assertion (A)
The assertion states that "Barium is not required for normal biological function in human beings."
- This statement is true. Barium is not an essential element for human biology. Unlike some other elements, such as calcium or magnesium, barium does not play a critical role in biological processes in humans.

### Step 2: Analyze the Reason (R)
The reason states that "Barium does not show variable oxidation states."
- This statement is also true. Barium, being an alkaline earth metal (Group 2), typically exhibits a fixed oxidation state of +2. Alkaline earth metals do not show variable oxidation states like transition metals do.

### Step 3: Determine the Relationship Between A and R
Now we need to evaluate the relationship between the assertion and the reason:
- While both statements are true, the reason provided does not explain why barium is not required for biological functions. The lack of variable oxidation states is a characteristic of barium as an alkaline earth metal, but it does not relate to its biological necessity.

### Conclusion
- Both the assertion (A) and the reason (R) are correct, but the reason is not the correct explanation for the assertion. Therefore, the answer to the question is that both A and R are true, but R does not explain A.

### Final Answer:
- Both assertion and reason are correct, but the reason is not the correct explanation for the assertion.

---