Explanation: The characteristic impedance (ZO) of a transmission line is a fundamental property determined by the physical geometry and dielectric material between its conductors. For a lossless line, it's defined by the square root of the ratio of its distributed inductance (L) to its distributed capacitance (C). To calculate ZO: 1. Convert the given values to standard units: * L = 250 microhenries = 250 × 10⁻⁶ H * C = 1000 picofarads = 1000 × 10⁻¹² F = 1 × 10⁻⁹ F 2. Apply the formula ZO = √L/C: * ZO = √( (250 × 10⁻⁶ H) / (1 × 10⁻⁹ F) ) * ZO = √( 250 × 10³ ) * ZO = √250,000 * ZO = 500 ohms Therefore, the impedance total (ZO) is 500 ohms. Options A, B, and D are incorrect as they do not result from the correct application of the formula with proper unit conversions.