A
It depends on the connector it uses (I don't have one, so I don't know), but if it uses a microUSB connector, and your phone does too, use the phone's charger. If not, you'll have to buy a charger that will fit. (Don't worry if the charger is capable of more current than the original, only if it's only capable of less. The S3 won't draw more than it's designed to.)