here is an easier way - because the rules are so complex...just fill out this 5 minute IRS tooliu
it will provide the answer:
https://www.irs.gov/help/ita/whom-may-i-claim-as-a-dependent
@Mike9241 - while I agree your answer is broadly correct, it infers that if the dependent is between 19 and 24 years old AND a student the individual is still a dependent, but that is only true if 'student' is more than a 'half time' student, is US citizen, has a SS#, etc... so best to use the IRS Tool for completeness
