"The gold rush of 1849 inspired the railroad companies to try to get trains to California" best explains a reason people wanted to build a railroad across the United States.
Answer: Option D
Explanation:
The gold coverage brought some 300,000 people from other parts of the U.S and overseas into California. This incident act as in ignition point for railroad companies to establish rail roots to California.
The Gold Rush had dramatic effects on Indigenous Californians and exacerbated the deterioration from disease, malnutrition and the California Genocide in the Native American populations. James W. Marshall was discovered the gold at Sutter's Mill, Coloma, California. This was occurred from 24 January 1848 to 1855.