A : Influx of ions into inner space of cells is an active process.
R : Ions are available for free exchange in free space.

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion.
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion.
C. If Assertion is true statement but Reason is false.
D. If both Assertion and Reason are false statements.

Answer

To solve the assertion and reason question, we need to analyze both statements separately and then determine their relationship.

### Step-by-Step Solution:

1. **Understanding the Assertion (A)**:
- The assertion states that "the influx of ions into the inner space of cells is an active process."
- This is true because the movement of ions such as sodium (Na+) and calcium (Ca2+) into the cell typically occurs against their concentration gradient.
- Active transport mechanisms, such as ion pumps, require energy (usually from ATP) to move ions from an area of lower concentration (outside the cell) to an area of higher concentration (inside the cell).

2. **Understanding the Reason (R)**:
- The reason states that "ions are available for free exchange in free space."
- This statement is also true. In biological systems, ions can move freely in the extracellular space and can be exchanged between different ions through various mechanisms, such as ion channels and pumps.

3. **Analyzing the Relationship**:
- While both statements are true, the reason does not provide a correct explanation for the assertion.
- The assertion discusses the active transport of ions into the cell, while the reason talks about the availability of ions for exchange in the free space, which does not directly explain why the influx is an active process.

4. **Conclusion**:
- Since both the assertion and reason are true, but the reason does not explain the assertion, the correct answer is that both statements are true, but the reason is not the correct explanation of the assertion.

### Final Answer:
- Both assertion and reason are true, but the reason is not the correct explanation of the assertion. Therefore, the answer is option B.