If the means of the two classes are 72 and 69, when we combine the classes, the mean will be somewhere between 69 and 72.
Using both Statements, it might be true that in class B, we have 31 students with a grade of "62", and one student with an astronomically high grade (high enough to make the mean 69). Then if we just have four students in the other class with a grade of exactly "62", the median of the two classes combined will be 62, since 35 values, more than half of the values in the set of grades, will equal 62. If more than half of the values in a data set are equal to some number k, then that value k is always the median of the set. So the median can be less than the mean when we combine the classes. But it's also possible that 36 of the grades in class A are "75" (and one grade is so low as to make the mean 72), which would ensure that 75 is the median of the two classes combined no matter what class B is like, and the median can exceed the mean. So the answer is E.
I'm not assuming the grades need to be between 0 and 100, since the question doesn't tell us that the grades are restricted in any particular way.