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-