An option set is a particular configuration of settings for one of the option groupings. In a given Project Options set, for example, you might choose to show GO TO statements in the Interactive Analysis Program Control Flow tool, while in the other Project Options sets you would not.
Option sets let you switch back and forth between configurations in the same session, without having to change settings manually. You can also use them to ensure uniform results across your team by sharing customized settings with team members.