I can’t figure out how to identify the primary key of one of my entities. The scenario is a diagram for a national honor’s society, and the entity in question is that of “office”.

There are several offices in each chapter.
Each office can belong to only one Chapter.
An office also contains such positions as President or Treasurer.
The office has a Title, Job Description, and Election Date.
Most Offices are managed by one of the chapter members, however there are times when an office will be unfilled.

what’s the pk here? is it office title? what’s the difference between title and position? if i choose title for the pk, how do i differentiate that from position?

i was thinking of using the office title as pk, but i understand enough of erd to know that it’s not unique enough, considering there are positions within a title.