The correct answer is Gold was discovered in the Sierra Nevada Mountains.
The California Gold Rush began after 1849 when gold was discovered at Sutter's Mill. After this, thousands of American citizens made the long trek across the country to California in hopes of finding gold. As it is today, gold is an extremely valuable resource that could potentially make individuals rich quickly. This expansion into California also resulted in the development and admittance of California as a US state in 1850.
