What was the significance of the transcontinental railroad

The First Transcontinental Railroad -built between 1863 and 1869- streched from the East Coast to the West Coast of the United States. This new means of transport implied that people no longer needed to travel for months to reach the other coast, because they could travel faster, safer and cheaper by this train. Also, mail, supplies and trade goods could now be shipped across the country.

i think the answer is a and i hope this ; ))

to act quickly in times of danger to the united states

because you have to act quickly if you want to live/survive.