Current readings of Ammeter
Given that two voltage sources have the same voltage (4 volts) and series impedance (1 ohm), it is clear that A1 and A3 must have the same current and that both the currents (A1 and A3) cannot be zero amps. That leaves (1) as the only feasible answer.

If you combined the two identical sources in parallel (which of course they are because perfect ammeters have zero impedance), you reduce the problem to two voltage sources; a 3 volt source in series with 1 ohm and a 4 volt source in series with 0.5 ohms; a net impedance of 1.5 ohms with 1 volt net across it.

This then leads to a current flow of 0.66667 amps into the 3 volt source. In other words 1/3 amp each from the two 4 volt sources via their respective 1 ohm resistors.