The primary reason that railroad leaders consolidated their lines in the 1880s was to reduce competition and increase efficiency. This is the first choice. By merging and consolidating smaller railroad companies into larger ones, they aimed to eliminate duplicate routes and services, thereby streamlining operations and reducing costs. This consolidation allowed for better coordination and control over the railway network, resulting in improved efficiency and increased profits for the railroad companies. The other options mentioned, such as keeping from becoming "too big too quickly," ensuring vertical integration, or increasing rapid construction of railroad lines, were not the primary motivations for railroad consolidation in the 1880s.
