A survey of sixth-grader students recorded how many hours students studied each week. The histogram below displays the collected information. A histogram titled Study Time has number of hours on the x-axis and number of students on the y-axis. 7 students study 0 to 1.99 hours; 6 study 2 to 3.99 hours; 3 study 4 to 5.99 hours; 4 study 6 to 7.99 hours; 1 studies 8 to 9.99 hours.

Which interval shows the greatest number of students?
0 - 1.99
2 - 3.99
4 - 5.99
6 - 7.99