A:
Any small or average size headphones with a connector that fits in the headphones plug in the back, next to the one for AUX plug-in.
The kind of headphones that students use at school on a computer.
Depending on what the sound quality you want, you can buy a small size headphones covering both ears to a larger, fancier and more expensive kind. Just make sure that the connector fits in the plug (If it's too big, then buy an adapter at an electronics store - Best Buy, Radio Shack, etc ...-.