The ADM decided to resign when he was . . . . . . . . for promotion to DM.

The correct answer is C. passed over.

To pass over someone means to overlook them for a promotion or other opportunity. In this case, the ADM was passed over for promotion to DM, which means that he was not chosen for the position. This may have been due to a number of factors, such as his performance, his qualifications, or the decision of the hiring committee.

The other options are incorrect. To pass off something means to pretend that it is something else. To pass out means to faint. To pass by means to go past something without stopping.

I hope this helps! Let me know if you have any other questions.