Marking menu options?


I have a project in OpenGL I’m supposed to do for school. One of the program requirements is that we mark which menu option (using a drop down menu that opens with RMB click) with a “" (example: If I am viewing the model in “perspective” projection mode, the menu option for “perspective” should have a "” next to it).
The thing is, I don’t know how to modify menu options while the program is running so this happens. Does anyone know how to do that? I don’t want to change what the menu options do, I just want to change the text that is displayed for the menu options.
If you know what function I should use, could you provide an example of it in use (using something like I said above)? Sometimes the basic function outlines don’t really give me much of an idea on how I’m supposed to use them.