The American Community Survey (www.census.gov/acs) provides data every year about communities in the United States. Addresses are

Question:

The American Community Survey (www.census.gov/acs) provides data every year about communities in the United States.
Addresses are randomly selected, and respondents are required to supply answers to a series of questions.
a. Which of the sources of data best describe the American Community Survey?
b. Is the American Community Survey based on a sample or a population?