Chess Opening Theory/1. e4/1...c5/2. Nf3/2...a6/3. c3

=Sicilian - O'Kelly variation - Venice System ("Enhanced" Alapin)=

3. c3
The only line for black that even approaches equality (by winning percentage) is 3. ... e6. In every other line it seems white has a much easier time of it, with win percentages approaching double that of black. This can be referred an "enhanced" Alapin based on white getting an extra developed Knight due to black's essentially wasted a6.

Theory table
1.e4 c5 2.Nf3 a6 3.c3