Which of the Following Would Be an Example of the Type

Multiple Choice

Which of the following would be an example of the type of data known as "available data"

A) administering a questionnaire to the college students available to the researcher in her classes
B) using information in the files of a social service agency to study the social factors associated with unwanted pregnancies
C) using an availability sample as a means of collecting subjects for an experiment
D) making unobtrusive observations of inmates of a prison during their recreation periods