How has nevada economy changed over the past 100 years?

At the beginning of the 20th century, Nevada was struggling with a 20-year depression. When the veins of gold, silver and copper dried up, the mining industry closed and people left Nevada. There were so few people left it hardly qualified to be called a state. In March 1931, Nevada legalized gambling in their desperate move to raise revenues. Also in that month, construction of the Hoover Dam began. This sure and steady supply of water and cheap electricity sent flocks of people back to Nevada. With the advent of World War II, the United States built their military bases in the West and Southern Nevada was a suitable venue. 1,000 homes were built by the federal government to house a workforce of 10,000 for a magnesium processing plant. After the war, resort hotels began to crop up across the Southern Nevadan desert. The interstate system made travelling to Nevada easy. After the creation of the Nevada Gaming Commission, the state started to attract legitimate investors. Nevada was one of the greatest economic success stories in the 20th century. 

The answer is c. hope that