The correct answer is A) Chinese.
The immigrants that were in charge of shaving down bedrock for the railroad were Chinese.
The Pacific Railroad Act of 1862 allowed the construction of a transcontinental railroad to connect the East coast of the United States with the West coast. The Union Pacific Railroad and the Central Pacific were the two companies that could receive the task to accomplish this important fear and hired many Chinese immigrants to do the hard work. They worked for seven years to connect the railroads from Omaha, Nebraska to Sacramento, California, until they finally met on May 10, 1869, in Promontory Utah.