To determine the relationship between the supply voltage and the total circuit current in a parallel RC circuit connected to a single-phase AC supply, we need to consider the individual components within the circuit:

1. Resistor (R): In an AC circuit, the current through a resistor is always in phase with the voltage across it. This means that there is no phase difference between the current and the voltage.
2. Capacitor (C): In an AC circuit, the current through a capacitor leads the voltage by 90^\circ. This occurs because the capacitor needs to charge up when the voltage is applied, introducing a phase shift where the current peaks faster than the voltage.
3. Parallel RC Circuit: In a parallel RC circuit, the total current is the phasor sum of the currents through the resistor and the capacitor. Since the current through the capacitor leads the voltage by 90^\circ and the current through the resistor is in phase with the voltage, the overall current leads the supply voltage. Therefore, the capacitive effect predominates the phase relationship.

As the current through the capacitor leads the supply voltage, the overall relationship between the supply voltage and the total circuit current in a parallel RC circuit is that the current leads the voltage. This is why the correct answer to the question is "current leads the voltage."