There is actually quite a lot of theory behind c3 sicilian and it's thought to be one whites best alternatives to a regular open sicilian. White strives for a classical pawn centre preparing to push his d pawn with the support of c3.
A good reply to 2.c3 for black is to simply play d5 not allow white to have a nice pawn center. It should be noted that after he captures 3.exd5 black can safely lodge his queen on d5 for the time being because the c pawn blocks the knight making d5 a difficult place to effectively get at.
after 1.e4 c5 2.c3 what are some possible lines that may follow? thanks