Final answer:
The significant event was the California Gold Rush that began in 1848 but saw a huge number of prospectors, known as Forty-Niners, arriving in 1849 to find gold in California.
Step-by-step explanation:
The significant event that took place when gold was unearthed in the hills above Lake Tahoe in 1849 was a) The California Gold Rush. On January 24, 1848, gold was discovered at Sutter's sawmill in California, and by 1849, thousands of individuals known as Forty-Niners headed west in search of gold. This period led to a cycle of boom and bust through the area as gold was discovered, mined, and stripped. While the subsequent Comstock Lode discovery in 1859 in Nevada signified the first significant silver find in the country, it was the gold discovery near Lake Tahoe in 1849 that marked the beginning of the California Gold Rush.
The significant event that took place when gold was unearthed in the hills above Lake Tahoe in 1849 was a) The California Gold Rush. This event was characterized by the discovery of gold in California, which led to a massive influx of people from around the world hoping to strike it rich. The gold rush had a profound impact on the development of California and the United States as a whole.