the question on your return is can you be claimed as a dependent. the fact that your parents didn't claim you has no bearing on how you answer. if you can be claimed you must mark the box yes.
here are the rules under which they could have claimed you as either a qualifying child or qualifying relative. again in they could claim you, you can't claim yourself.
you could be claimed as a qualifying child if all these tests are met
• you have the same principal abode as the other party for more than ½ the tax year. Temporary absences like for school are ignored
• If not a full-time student, under 19 at the end of the tax year. If a full-time student under 24 at the end of the tax year.
• you haven't provided over ½ your own support
• you didn't file a joint return unless there was no tax liability but merely filing joint to facilitate refund of taxes withheld or estimates paid
or as you could be a qualifying relative if all these tests are met
> your related or if not lived with the other party for the entire year. again temporary absences like for school are ignored
• your gross income for 2018 less than $4,150
• the other party provided over ½ your support
• you aren't a qualifying child of another taxpayer
