; (C) mixed commercial use or community-based facility and residential use; and (D) mobility options to reduce personal vehicle miles used or green house gas emissions. (4) Priority investment area The term priority investment area means an area certified as a priority investment area in an eTOD and Mobility Plan. (5) Secretary The term Secretary means the Secretary of Transportation. (6) State transportation authority The term State transportation authority means the State agency or official responsible under the direction of the Governor of the State or a State law for preparation, maintenance, coordination, and administration of the State transportation, rail, and public transportation plan. (b) Applicability of chapter 53 definitions In this Act, any term defined in chapter 53 of title 49, United States Code, has the meaning given that term in that chapter. 3. Office of Equitable Transit-Oriented Development (a) Establishment The Secretary shall establish within the Department of Transportation an Office of Equitable Transit-Oriented Development and Mobility. (b) Responsibilities The responsibilities of the Office of Equitable Transit-Oriented Development and Mobility are— (1) to establish and manage the eTOD and mobility grant program established under section 5; (2) to certify eTOD and Mobility Plans; (3) to certify priority investment areas included in such Plans