Final answer:
Ariel cannot claim Christopher as a dependent due to the Age test; he is 25 and exceeds the IRS age requirement for a qualifying child. Pat, who is 22, still meets the age requirements (option a).
Step-by-step explanation:
The question asks which test will prevent Ariel from claiming both Christopher and Pat as dependents on her taxes. Considering the details provided, both Christopher and Pat are full time students and have full tuition scholarships, living at school during the school year. Given Christopher's age of 25 and that he graduated in June, the relevant test that would prevent Ariel from claiming him as a dependent is the Age test.
This is because the IRS rules state that to be considered a qualifying child, a student must be under the age of 24 at the end of the calendar year unless permanently and totally disabled. Since Christopher is 25, he exceeds the age requirement to be classified as a dependent under the qualifying child criteria. Pat, who is 22, meets the age criteria and would likely continue to be considered a dependent provided he meets the other criteria.
Hence, the answer is option a.