a collection of Option Buttons (sometimes called Radio Buttons ) placed within a Frame (in fact option buttons on a VBA UserForm do not need to be placed within a frame to work as a group, but it helps the user to understand that they work together)
On a form or dialog box, a group of controls where only one of them can be selected at once. Usually the controls inside an option group are option buttons but they can also be toggle buttons or check boxes.