All banks, trust companies, bankers, savings banks and institutions, building and loan associations, savings and loan associations, investment companies, and other persons carrying on a banking or investment business; all insurance companies, insurance associations, and other persons carrying on an insurance business; and all executors, administrators, curators, trustees, and other fiduciaries may legally invest any sinking funds, moneys, or other funds belonging to them or within their control in any bonds or other obligations issued by a municipality or county pursuant to this chapter or by any urban redevelopment agency or housing authority vested with urban redevelopment project powers under Code Section 36-61-17, provided that such bonds and other obligations shall be secured by an agreement between the issuer and the federal government, in which the issuer agrees to borrow from the federal government and the federal government agrees to lend to the issuer, prior to the maturity of the bonds or other obligations, moneys in an amount which (together with any other moneys irrevocably committed to the payment of interest on the bonds or other obligations) will suffice to pay the principal of the bonds or other obligations with interest to maturity thereon, which moneys under the terms of the agreement are required to be used for the purpose of paying the principal of and the interest on the bonds or other obligations at their maturity. Such bonds and other obligations shall be authorized security for all public deposits. It is the purpose of this Code section to authorize any persons, political subdivisions, and officers, public or private, to use any funds owned or controlled by them for the purchase of any such bonds or other obligations. Nothing contained in this Code section with regard to legal investments shall be construed as relieving any person of any duty of exercising reasonable care in selecting securities.