If you agree to be re-contacted for this purpose and are then invited to participate in future research, you can still decline to participate at that point in time.
Os cytunwch y cawn ailgysylltu â chi at y diben hwnnw, ac rydych wedyn yn cael eich gwahodd i gymryd rhan mewn ymchwil yn y dyfodol, gallwch wrthod cymryd rhan ar yr adeg honno.