AJo in BB facing an MP1 raise and a SB call. Reraise, call, or fold?

[TiltsMcFabulous]

If you are dealt AJo in the BB in a normal name (not too tight or too loose), 7-handed, and MP1 raises while the SB cold calls (in a 1/3 blind structure), what is hero's action? Call, raise or fold? Assume both the raiser and caller are unknowns.

I'd like to hear why if you can provide that advice too please.

Thanks.

~ Tilts