2. The National Agricultural Statistics Service conducts studies of the number of acres devoted to farms in each county of the United States. Suppose that we divide the U.S. into the four census...

Extracted text: 2. The National Agricultural Statistics Service conducts studies of the number of acres devoted to farms in each county of the United States. Suppose that we divide the U.S. into the four census regions (Northeast, North Central, South and West), take a simple random sample of counties form each of the four regions, and combine all four simple random samples into one sample, which type of sampling design would have been used? Explain your answer.