Final answer:
Savannah may be eligible for the Earned Income Credit (EIC) as she provides full support to her permanently and totally disabled brother who lives with her and qualifies as her dependent. Therefore, the correct option is D.
Step-by-step explanation:
The student asked which tax credit is available to Savannah who provides 100% support to her permanently and totally disabled brother, Brock, who is not married and lives with her. The correct answer is D. Earned Income Credit. Although Savannah provides support for Brock and he qualifies as her dependent, other credits like the Child Tax Credit and the Additional Child Tax Credit are specifically for dependents who are under the age of 17.
The Adoption Credit is irrelevant in this context as it applies to expenses related to the adoption of a child. On the other hand, the Earned Income Credit (EIC) is available to taxpayers who support qualifying relatives, which may include a sibling like Brock if they meet certain requirements such as age, disability status, residency, and dependency rules. Since Brock is permanently and totally disabled and lives with Savannah, she may be eligible for the EIC.