A

Step 1: Identify the components in the circuit. There are 4 batteries, each of 5V, and an internal resistance of 0.2 ohm per battery.
Step 2: Calculate the total voltage of the batteries in series:
Total Voltage = 4 * 5V = 20V.
Step 3: The total internal resistance of the batteries when connected in series is:
Total Internal Resistance = 4 * 0.2 ohm = 0.8 ohm.
Step 4: The total resistance seen by the battery circuit, considering only internal resistance, is 0.8 ohm.
Step 5: Use the formula V = IR to find the reading on the ideal voltmeter when connected across the batteries:
The current (I) flowing through the circuit can be calculated by the total voltage divided by total internal resistance: I = Total Voltage / Total Internal Resistance = 20V / 0.8 ohm = 25A.
Step 6: The voltage drop across the internal resistance can be calculated using V_drop = IR = 25A * 0.8 ohm = 20V.
Step 7: The voltmeter measures the output voltage across the batteries, which is Total Voltage - Voltage Drop: V = 20V - 20V = 0V.
Therefore, the reading in voltmeter V is 0V.