28. The finding that twice as many Millennials report having no sexual partners since the age of 18, compared with those born in the 1960s and 1970s, was derived from the use of which research method?

This was derived from the use of "SURVEY RESEARCH METHOD".

Explanation: Survey research method is a type of research method that is used to get a particular Information from a group of people, using a list of questions. Survey research method simply means to get a particular Information from people, by asking questions.

Jean M. Twenge a professor of psychology at San Diego State University, and many others, conducted a research, that teenagers of nowadays dont have sexual partners before the age of 18, when compared to those born in 1960s and 1970s. Their conducted this research using the general social survey, by sending a list of questions to people, and using their response to conclude a result.

the answer for 3 is b and the answer for 4 is d

d) iowa i believe is the answer