Assertion: When `AC` circuit contain resistor only, its power is minimum.
Reason: Power of a circuit is independent of phase angle.

Options

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

Explanation

To solve the question, we need to analyze the assertion and the reason provided.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that when an AC circuit contains only a resistor, its power is minimum.
- In an AC circuit, the power (P) is given by the formula:
\[ P = V \cdot I \cdot \cos(\phi) \]
where \( V \) is the voltage, \( I \) is the current, and \( \phi \) is the phase angle between the voltage and current.

2. **Analyzing the Power in a Resistor Only Circuit**:
- In a circuit with only a resistor, the phase angle \( \phi \) is 0 degrees because the voltage and current are in phase.
- Therefore, \( \cos(0) = 1 \).
- This means the power is:
\[ P = V \cdot I \cdot 1 = V \cdot I \]
- Hence, the power is maximum when the circuit contains only a resistor, contradicting the assertion.

3. **Understanding the Reason**:
- The reason states that the power of a circuit is independent of the phase angle.
- However, from the power formula, we see that power is indeed dependent on the phase angle through the term \( \cos(\phi) \).
- If \( \phi \) changes, the power will change accordingly, indicating that the reason is also incorrect.

4. **Conclusion**:
- Since both the assertion and the reason are incorrect, the correct choice among the given options would be the one that states both are false.

### Final Answer:
Both the assertion and the reason are false.