Any student who is not required to hand in written homework based on the reading assignments in a course will not complete all of the reading assignments. Even highly motivated students will neglect their reading assignments if they are not required to hand in written homework. Ttherefore, if the students in a course are given several reading assignments and no written assignments, no student in that course will receive a high grade for the course. The conclusion of the argument follows logically if which one of the following is assumed? ['Any student who completes all of the reading and written assignments for a course will earn a high grade in that course.', 'No student who completes anything less than all of the reading assignments for a course will earn a high grade for that course.', 'All highly motivated students who complete all of the reading assignments for a course will receive high grades for that course.', 'Some highly motivated students will earn high grades in a course if they are required to hand in written homework on their reading assignments.']