I believe the answer is Compression C
Since the wires are made up of the same material, the resistivities will be the same.
The rate of the inlet pipe is 1/18 of the pool volume per hour while the drain pipe is 1/36 volume per hour.
The net rate meaning if the two pipes work simultaneously is 1/18 – 1/36 = 1/36 of the pool volume per hour.The equation to know the t for filling 1/3 of the remaining volume of the pool is 1/36 * t = 1/3Solving for t is through cross multiplication. Thus it gives us t = 12.
