(1) A rural development authority shall provide by resolution that all moneys deposited by it shall be secured by: Obligations of the United States or of the state of a market value equal at all times to the amount of the deposits;
(2) Any securities in which savings banks may legally invest funds within their control;
(3) An undertaking with such sureties as shall be approved by the authority faithfully to keep and pay over upon the order of the authority any such deposits and agreed interest on them; or
(4) Other obligations allowed by law.
(5) All banks and trust companies are authorized to give any such security for such deposits.