What do I claim if my parent does not remember if or when they claimed me for the American Opportunity Credit or the Hope Credit?

I assume that my parents would have claimed these credits the four years that I was in school for my undergrad degree, but they do not remember if they claimed these credits and they do not remember for how many years they would have been claimed. Since it was available, I can't imagine that they wouldn't have claimed them- but I'm not sure how I should file with this gap in information.