The correct answer is Option A) providing supplies to build the tracks and support the workers.
The transcontinental railway one of the biggest projects of its kind at the time. The idea was to connect the rapidly industrializing North of the country with the expanding, sparsely populated Western region.
It was 3,077km long and was able to connect the city of Omaha in Nesbraska with San Franciso Bay, completely changing the demographics of the country for the next 50 years.
It was a challenging project with the most diffuclt part being the logistics of constant supply for building and for the workers.