Which factor most contributed to delays in construction for the Central Pacific Railroad?

a shortage of supplies

intense summer heat

long stretches of desolate landscape

conflicts with American Indians

a shortage of supplies

Explanation:

The main problems that the Central Pacific Railroad construction faced was the fact that the country was experimenting a shortage of supplies on the main metals needed to construct the railroad, and since you can't do you job iy you don't have the things to work with, the construction got delayed because of that shortage.