The correct answer is: C. 100-200 ohms.
Surge impedance is the ratio of the voltage to the current of a surge traveling on a transmission line. It is a complex number, and its real part is the resistance and its imaginary part is the reactance. The surge impedance of an overhead line is typically in the range of 100-200 ohms.
The surge impedance of an overhead line is important because it determines the reflection coefficient of a surge traveling on the line. The reflection coefficient is the ratio of the reflected wave to the incident wave. If the surge impedance of the line is equal to the characteristic impedance of the line, then there will be no reflection. However, if the surge impedance of the line is not equal to the characteristic impedance of the line, then there will be a reflection.
The reflection coefficient can cause problems if it is not taken into account. For example, if the reflection coefficient is large, then it can cause a voltage spike on the line. This voltage spike can damage the equipment connected to the line.
Therefore, it is important to know the surge impedance of an overhead line in order to design the line properly and to avoid problems caused by reflections.
The other options are incorrect because they are not in the typical range of surge impedance for an overhead line.