Nucleophilic substitution reactions are common in organic chemistry and involve the replacement of one nucleophile with another in a molecule. These reactions can occur in two main pathways: bimolecular nucleophilic substitution (S_N2) and unimolecular nucleophilic substitution (S_N1). The key distinction between these pathways is the mechanism by which the nucleophile attacks the substrate.

Consider the substrate 1-bromobutane (C₄H₉Br) undergoing a nucleophilic substitution reaction with hydroxide ion (OH^-). Which of the following statements correctly describes the outcome of this reaction?