At a high school, the cafeteria staff provides optional comment cards to students eating in the cafeteria. Students who wish to make a comment can obtain and fill out a comment card and return it to a drop box in the front office. At the end of the semester, the staff analyzes the responses and finds that 72% of the students who filled out a comment card recommend major changes to the food selection. What conclusions can the cafeteria staff draw from these responses?A) Since all of the students had an opportunity to respond, this is evidence that a majority of all the students supports major changes. B) The cafeteria staff should not use the results to draw any conclusions since some students may not have filled out a comment card, which is non-response. C) If the students recorded their grade level with their response, the staff could make the original sample a stratified sample and use the responses to learn what proportion of each grade recommends major changes to food selection. D) The responses were from a voluntary response sample, so the cafeteria staff should not use the results to draw any conclusions. E) The opportunity to fill out comment cards should be offered to students at all high schools in the school district to get a larger sample size, which will make the results more reliable,