Assertion : `Ca^(++)` and `K^(+)` ions are responsible for maintaining proper osmotic pressure balance in the cells of organism.
Reason : Solutions having the same osmotic pressure at same temp are called isotonic solutions.

Options

A. If both assertion and reason are true and the reason is the correct explanation of the assertion.
B. If both assertion and reason are true but reason is not the correct explanation of the assertion.
C. If assertion is true but reason is false.
D. If asserrion is false but reason is true.

Explanation

To solve the given assertion and reason question, we will analyze both statements and determine their validity step by step.

### Step 1: Analyze the Assertion
The assertion states: "Ca^(++) and K^(+) ions are responsible for maintaining proper osmotic pressure balance in the cells of organisms."

- **Understanding Osmotic Pressure**: Osmotic pressure is the pressure required to prevent the flow of water across a semipermeable membrane due to solute concentration differences. It is crucial for maintaining cell turgor and overall homeostasis in organisms.
- **Role of Ions**: While K^(+) ions do play a significant role in osmotic balance, Ca^(++) ions are not the primary ions responsible for this function. Instead, Na^(+) ions are more commonly associated with osmotic pressure regulation in cells.

**Conclusion for Assertion**: The assertion is **false** because it incorrectly identifies Ca^(++) as a key ion for osmotic pressure balance, whereas Na^(+) is more relevant.

### Step 2: Analyze the Reason
The reason states: "Solutions having the same osmotic pressure at the same temperature are called isotonic solutions."

- **Definition of Isotonic Solutions**: Isotonic solutions are indeed defined as solutions that have the same osmotic pressure when measured at the same temperature. This means that there will be no net movement of water across a semipermeable membrane when these solutions are separated.

**Conclusion for Reason**: The reason is **true** as it correctly describes the concept of isotonic solutions.

### Final Conclusion
- **Assertion**: False
- **Reason**: True

Thus, the correct answer to the question is that the assertion is false and the reason is true.

### Answer:
The answer is that the assertion is false and the reason is true (Option 4).

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