But overall, both. Affects only some students only. Because teachers are rarely specific to the individual, to teach and to observe the behaviour of students only.
But overall, both of the above. Affect only students only. It is not specific to the individual teacher to teach a whole and to observe the behavior of students.
However, by including the two mentioned. Some students only affects only. Because the teacher is not specific to the individual, to teach the overall, and to observe the behavior of students only.