On July 1, a group of students are standing in rows, with 20 students in each row. On July 2, the same group is standing with all of the students in one long row. This process continues through July 10 with a different number of students per row each day. However, on July 11, they cannot find a new way of organizing the students. What is the smallest possible number of students in the group?
40
60
80
100
120
