Passage
In the early nineteenth century, local time was determined by the sun's position at noon in each town, leading to a patchwork of hundreds of distinct local times across the United States. As railroad networks expanded rapidly in the 1840s, this localized time-keeping system created dangerous scheduling conflicts and train collisions on shared tracks. To coordinate train movements and ensure safety, railroad managers required a unified time system. The development of the electric telegraph in the 1840s provided the technological infrastructure needed to address this crisis. By transmitting time signals instantaneously along telegraph lines from astronomical observatories to stations, railroads could synchronize clocks across vast distances. This capability directly enabled the major railway companies to establish four standardized time zones in 1883, replacing the chaotic localized systems. Consequently, standard time, which began as a pragmatic measure to facilitate safe railway logistics, eventually became adopted by the general public and formalized by federal law.
Based on the passage, the establishment of standardized time zones in 1883 was directly made possible by which of the following?
- Athe rapid expansion of railroad networks across the United States in the 1840s
- the ability to transmit instantaneous time signals from observatories using telegraph linesAnswer
- Cthe public adoption of standard time forcing observatories to invent the electric telegraph
- Dfederal mandates requiring towns to establish local time based on the sun's position