The purpose of a parallel circuit resonance is to magnify

Answer: Option B

In a parallel circuit resonance, the purpose is to magnify voltage.

Resonance in a parallel circuit occurs when the impedance of the circuit becomes purely resistive, causing the current to be magnified and the voltage across the circuit elements to be maximized.

Option A: Current. While resonance does affect current, the primary purpose is to magnify voltage.

Option B: Voltage. This is correct as resonance in a parallel circuit results in the amplification of voltage.

Option C: Power. While resonance can affect power, its primary purpose is not to magnify power but rather voltage.

Option D: Frequency. Resonance does not magnify frequency but occurs at a specific frequency where the impedance of the circuit is minimized.

Therefore, the correct answer is Option B: Voltage.