A college official conducted a survey to estimate the proportion of students currently living in dormitories about their preference for single rooms, double rooms, or multiple (more than two people) rooms in the dormitories on campus. Which of the following does NOT affect the college official's ability to generalize the survey results to all dormitory students. a. Five thousand students live in dormitories on campus. A random sample of only 500 were sent the survey.
b. The survey was sent to only first-year students.
c. Of the 500 students who were sent the survey, only 160 responded.
d. All of the above present a problem for generalizing the results.