Explanation: In a vacuum tube circuit, the grid bias voltage can be developed by the flow of grid current (Ig) through a grid leak resistor. This is a common method, especially in transmitting tubes where the grid is driven positive on peaks, causing grid current to flow. According to Ohm's Law, the voltage drop (V) across a resistor is the product of the current (I) flowing through it and its resistance (R): V = I * R. In this case: * Grid current (Ig) = 10 mA = 0.010 A * Grid leak resistance = 5000 ohms Calculating the grid bias voltage: V = 0.010 A * 5000 ohms = 50 V This 50 V drop creates a negative bias on the grid relative to the cathode, establishing the tube's operating point. Therefore, 50 V is the correct grid bias voltage.