When the options are static items (not database driven) and they can fit on the screen (about 2-5 items), they should be radio buttons.
For a ComboBox, user needs 2 clicks to change the value:
For an options group, user can see all the available options without clicking, and select the option with just a click.
❌ Figure: Bad example - ComboBox is used for "Job Type" where it contains only 2 options
✅ Figure: Good example - Radio Buttons are used and aligned vertically