In a certain school, students can choose whether to eat in the school’s cafeteria. A reporter working for the school’s newspaper polled students on their reactions to changes in the menu at the cafeteria. For each student leaving the cafeteria in one 30-minute time period, the reporter used a coin to determine whether to stop the student and ask how he or she felt about the new menu. In the reporter’s article it was stated that a random sample of the students showed that 89 percent of the school’s student population was happy with the new menu. Which of the following statements is true?

Because each student leaving the cafeteria was randomly selected and could choose to answer or not, this is a random sample of the student population, and the 89% is an accurate measurement of the school population's view of the new menu.

Because students self-selected whether to eat in the cafeteria, the sampling method might be biased and the sample might not be representative of all students in the school.

The survey would have been more effective if the reporter had collected the data in one 15-minute time period rather than in one 30-minute time period.

Because no treatment was imposed on the students eating in the cafeteria, one cannot make any conclusions about the new menu.