Final answer:
When working with single-phase voltage drop over a cable, it's essential to take into account both resistance and reactance, as they collectively determine the cable's total impedance in an AC circuit.
Step-by-step explanation:
When working with single-phase voltage drop over a cable, it's important to consider both resistance and reactance. This is because, in an electrical circuit, voltage drop can be the result of not just the resistive elements (ohmic), but also the inductive and capacitive elements that cause reactance. The total impedance of a cable in an AC circuit is a combination of both resistance (ohmic resistance) and reactance, which includes both inductive reactance (due to the presence of an inductor or the inductive properties of the cable itself) and capacitive reactance (due to the presence of a capacitor or the capacitive properties of the cable).
Ohm's law (V = IR) and the formula for power (P = IV) take into account just the resistance component, but in AC circuits, both resistance and reactance play a crucial role in determining the total impedance and therefore the actual voltage drop across a cable. For practical calculations relating to voltage drop, both resistance and reactance must be considered, meaning the correct answer to the question is C. To consider both resistance and reactance.