Answer:
E. the Union Pacific and Central Pacific
Explanation:
The First Transcontinental Railroad was known originally as the "Pacific Railroad" and was later called the "Overland Route". The railroad was a 1,912 mile continuous railroad line which was constructed between 1863 and 1869 and connected the existing eastern U.S. rail network at Council Bluffs, Iowa with the Pacific coast at the Oakland Long Wharf on San Francisco Bay.
The rail line was built by three private companies over public lands provided by extensive US land grants: The Western Pacific Railroad Company built 132 mi of track from Alameda/Oakland to Sacramento, California. The Central Pacific Railroad Company of California (CPRR) constructed 690 mi eastward from Sacramento to Promontory Summit, Utah Territory. The Union Pacific built 1,085 mi from Council Bluffs near Omaha, Nebraska westward to Promontory Summit.
