Explanation: The impedance of a series RC circuit is a complex quantity, combining resistance and reactance. Resistance (R) is the real component, while capacitive reactance (Xc) is the imaginary component, always negative for capacitors. 1. **Rectangular Impedance:** For a series circuit, impedance (Z) is R - jXc. Z = 300 ohms - j400 ohms. 2. **Magnitude:** The magnitude of impedance (|Z|) is calculated using the Pythagorean theorem: |Z| = sqrt(R^2 + Xc^2) |Z| = sqrt(300^2 + (-400)^2) |Z| = sqrt(90,000 + 160,000) = sqrt(250,000) = 500 ohms. 3. **Phase Angle:** The phase angle (theta) is found using the arctangent function: theta = arctan(Xc / R) theta = arctan(-400 / 300) = arctan(-1.333...) theta = -53.13 degrees (approximately). The negative sign indicates a capacitive circuit where current leads voltage. Therefore, the impedance in polar coordinates is 500 ohms, /-53.1 degrees. This matches option C. Options A and B have incorrect magnitudes. Option D has the correct magnitude but an incorrect positive angle, which would represent an inductive circuit.