Answer:
A. Gold was discovered in northern California.
Explanation:
Gold was discovered in California after the war with Mexico. It caused a frenzy , a rush to go to California to dig in rivers or mines and become rich. It was the so-called "gold fever" or "gold rush" that motivated thousands of people in the East Coast to venture into California. It wasn´t easy and safe, because the Panama Canal did not exist then. To go by land was dangerous because of the attacks of Indians. To go by sea, you had to take a ship and go to Cape Horn in the extreme of the Atlantic.
