HELP?!
The main factor that slowed construction of the Central Pacific railroad was
A: a shortage of supplies, which had to be shipped around South America.
B: intense summer heat that melted the railroad ties and tracks.
C: scarcity of wood used for building railroad ties and trestles.
D: conflicts with American Indians who closed down the tracks.

The correct answer is a shortage of supplies, which had to be shipped around South America.

Although the government gave land to the railroad companies to accelerate the development of a transcontinental railroad, there was still a challenge of supplies which slowed down the construction

thanks to  another person

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the 9th amendment

explanation: