The correct answer is D. Take the help of the head of the institution.
A teacher encounters various problems during his professional career. It is important for him to take the help of the head of the institution in such situations. The head of the institution can provide guidance and support to the teacher. He can also help the teacher to find solutions to the problems that he is facing.
The other options are not correct. Option A is not correct because resigning from the post is not a solution to the problems that the teacher is facing. Option B is not correct because doing research on the problem and finding a solution is not the responsibility of the teacher. Option C is not correct because avoiding the problematic situations is not a solution to the problems that the teacher is facing.
Therefore, the correct answer is D. Take the help of the head of the institution.