B. Gold was discovered in the Sierra Nevada Mountains
The California Gold Rush of 1949 was the time period in American history where gold was found in California, specifically the Sierra Nevada Foothills. 25 million ounces of gold were mined from there. People from across the country moved to California both in search of gold, but also to build mining industries and businesses specializing in selling supplies to the people searching for gold. After the end of the Gold Rush, many people remained settled in California because they either wanted too or they had spend most of their money attempting to find gold, were unsuccessful in doing so, and did not have the money to move back East.