A middle school held two types of lectures on literature and science, and statistics on students' participation in the lectures. It was found that among the first-year students, some students participated in all literature lectures, and some students participated in all science lectures. If the above statement is true, which of the following must be true? ? ['First-grade students attended all lectures.', 'Every first-grader attended at least one lecture.', 'Every lecture is attended by first-year students.', 'Some first-year students did not attend any lectures.']