The correct answer is: "US Department of Education"
The US federal goverment is the executive branch of goverment. It is in charge of enforcing the laws that have been previously drafted by the legislative branch. For example, the US goverment is in charge of enforcing the anti-discrimination legislation contained in the US Constitution (for example in 14th Amendment).
Considering the options provided in the question, the only one which represents a goveremnt body that operates at a federal level, is the US Department of Education. The other options represent goverment bodies that operate in inferior levels: state level, local level and instutional (high school) level.