Best response to the Sicilian Defense (B27)

1. e4 c5 2. Nf3 · Black to move

What is the best response to the Sicilian Defense (1. e4 c5 2. Nf3)? Black to move. See the top replies ranked by opening theory and real-game results, starting with d5.

The main theoretical reply is Nc6, reaching the Sicilian Defense: Old Sicilian.