Identify the substrate in the following reaction: A single step reaction is shown. A substrate with SMILES string CC(C)CCBr reacts with NaSH in the presence of CH₃CN to yield SMILES string CC(C)CCS plus NaBr. Select the answer from the options below.
1) CH₃CN
2) Br-
3) A bond line structure with SMILES string CC(C)CCBr.
4) Na⁺ HS-