In the in 1848, the u. s. acquired all or part of california, arizona, and nevada, as well as several other states.
a. treaty of guadalupe hidalgo
c. louisiana purchase
b. civil war
d. the california gold rush

a. Treaty of Guadalupe Hidalgo 

In the TREATY OF Guadalupe Hidalgo in 1848, the U.S. acquired all or part of California, Arizona, and Nevada, as well as several other states

NOT:
c. Louisiana Purchase 
b. Civil War 
d. the California Gold Rush