Best response to the French Defense: St. George Defense (C00)

1. e4 e6 2. d4 a6 · White to move

What is the best response to the French Defense: St. George Defense (1. e4 e6 2. d4 a6)? White to move. See the top replies ranked by opening theory and real-game results, starting with c4.

The main theoretical reply is c4, reaching the French Defense: St. George Defense, Three Pawn Attack.