Which of the following scenarios does not meet the age requirements for qualification as a dependent?

In determining the age requirements for qualifying as a dependent, it is essential to consider the specific criteria established by the IRS. A dependent must generally be either a qualifying child or a qualifying relative. For a qualifying child, the individual must typically be under 19 at the end of the year or under 24 if they are a full-time student. Here, option C presents a 28-year-old full-time student. Since this individual exceeds the age limit for being classified as a qualifying child based on the student's age, they do not meet the essential criteria for dependency.

In contrast, the other scenarios either clearly fit within the dependent criteria or involve individuals who are not disqualified solely based on age. The 17-year-old single mother qualifies as a dependent child, the 30-year-old with a permanent disability can qualify as a dependent relative, and a 9-year-old adopted child easily falls under the qualifying child category. Understanding these age specifications is crucial in determining who can be claimed as a dependent on a tax return.