For round conductors, cross-sectional area is expressed in circular mils. A circular mil is a unit defined so that the area of a circle with a diameter measured in mils equals the diameter squared, giving a direct link between diameter and area without extra factors. Since a mil is one thousandth of an inch, using circular mils lets you read the area from the diameter in mils as simply d^2. This convention is standard in electrical practice because it makes resistance, current capability, and related calculations straightforward. For example, a wire with a 20 mil diameter has an area of 400 circular mils. Using square mils would require multiplying by pi/4 to convert, and square inches are far too large for typical wire sizes. So the statement is true.

In a parallel circuit, each resistor has the same voltage across it, so Ohm’s law applies individually as I = V/R. Since the voltage is the same for every branch, the current through a branch is inversely proportional to that branch’s resistance: higher resistance means less current, lower resistance means more current. That’s why the quantity that varies inversely with current in this scenario is the resistance. The voltage across each resistor stays constant, while current shifts according to resistance; capacitance isn’t the controlling factor in this steady-state DC setup, and power relates to current and resistance via P = I^2R or P = VI, not the inverse relationship described.

Reluctance is the opposition to magnetic flux in a magnetic path, and it depends on the path’s length, cross-sectional area, and the material’s permeability. The statement treats reluctance as the measure of a material’s resistance to magnetism. That isn’t quite right, because reluctance isn’t a property of the material alone; it’s a property of the whole magnetic circuit, including geometry and the material’s ability to support flux. In formula terms, reluctance is ℜ = l/(μA). If the material has high permeability (μ large) or the path is short and wide, reluctance decreases, making flux easier to pass. If the path is long or narrow, or μ is low, reluctance increases. For a material’s tendency to become magnetized, permeability (and magnetic susceptibility) are the more direct measures. So the statement is false.

Current is conserved in a parallel circuit: the current from the source splits into the different branches, and those branch currents add together to give the total current flowing from the source. In other words, I_total = I_branch1 + I_branch2 + I_branch3 + … because each branch draws its own current based on its resistance and the same voltage across all branches. This is why the correct answer is the currents. The other quantities aren’t what sum across parallel branches: the resistance of multiple branches in parallel combines in a way that reduces the overall resistance (not a simple sum), the voltage across each branch is the same (not added), and power depends on both voltage and current rather than forming a simple sum of branch currents.