The best answer to the query is B. By working together voluntarily.
In 1883, railroad companies faced significant challenges due to the lack of standardized timekeeping, which led to confusion and safety issues across various networks. To address these problems, railroad companies voluntarily agreed to implement standardized time zones and timetables. This collaboration among various companies was crucial as it allowed for better coordination of train schedules and improved safety by reducing the risk of accidents caused by time discrepancies.
While there were external factors that influenced this standardization, such as the growing need for efficiency in transportation and communication, the primary mechanism by which the timetables were standardized was through the voluntary agreement between railroad companies rather than federal legislation, union actions, or the merging of companies.