The General Social Survey (GSS), Conducted by the National Opinion

The General Social Survey (GSS) , conducted by the National Opinion Research Center at the University of Chicago, is a major source of data on social attitudes in the United States. Once each year, 1500 adults are interviewed in their homes all across the country. The subjects are asked their opinions about sex and marriage, attitudes toward women, welfare, foreign policy, and many other issues.
The questions on the GSS are considered

A) samples.
B) variables.
C) individuals.
D) populations.