responsibility Any responsibility of the Secretary concerned described in paragraph (1) that is not explicitly assumed by the State in the memorandum of understanding shall remain the responsibility of the Secretary concerned. (c) Offer and notification A State that intends to offer to enter into a memorandum of understanding under this section shall provide to the Secretary concerned notice of the intent of the State not later than 90 days before the date on which the State submits a formal written offer to the Secretary concerned. (d) Memorandum of understanding A memorandum of understanding entered into under this section shall— (1) be executed by the Governor or the top-ranking transportation official in the State who is charged with responsibility for highway construction