Cause and effect designs identify how a certain set of conditions brings about a particular result

A university professor is conducting a study about why Americans watch a popular new sitcom. Which of the following groups would be a nonprobability sample for this research?

a. Students randomly selected from the professor's classes b. Subjects who are randomly selected from volunteers who responded to acommercial for the study that had been placed in the sitcom c. Volunteers who responded to a commercial for the study that had beenplaced in the sitcom d. All of the above

The primary collector and reporter of television ratings is a company known as

A. Arbitron. B. Telecount. C. Nielsen. D. Equifax.