The desire for access to natural and mineral resources and the hope of many settlers for economic opportunities or religious refuge led to an increased migration to and settlement in the west

(a) california gold rush
(b) religious refuge
(c) farmers can move west and make more money because they could get more land
(d) south wanted to expand slavery

A) California gold rush

Explanation:

The gold rush occurred form the period of 1848–1855, and was due to he dores of the people to access the wealth  and the natural resources which saw the rise and increase of the population rapidly.  As the case of the economic opportunities in the west.Development transport system influenced many more towards the west and they by increased the job rush and the population.