Spring Mountain College recently sent out a survey to the graduating class of 2003 asking that the graduates provide their class rank. Surprisingly, the survey results revealed that most of the students ranked in the top third of the class. The survey results would most likely be explained by which one of the following? ['All the graduates of 2003 responded to the survey.', 'Many of the respondents ranked in the lower half of the class.', 'A majority of the respondents ranked high in the graduating class.', 'All the graduates of 2003 had a positive experience while at Spring Mountain College.']