The state and all public officers, any county, municipality or other subdivision or instrumentality of the state, any political subdivision, any bank, banker, trust company, savings bank and institution, building and loan association, savings and loan association, investment company or any person carrying on a banking or investment business, any insurance company or business, insurance association and any person carrying on an insurance business, any executor, administrator, curator, trustee and other fiduciary, and any retirement system fund may legally invest any sinking funds, monies or other funds belonging to them or within their control in any bonds or other obligations issued by the district pursuant to the provisions of this chapter, and such bonds or other obligations shall be authorized security for all public deposits. It is the purpose of this section to authorize such persons, firms, corporations, associations, political subdivisions and officers, or other entities public or private, to use any funds owned or controlled by them, including but not limited to sinking, insurance, investment, retirement, compensation, pension and trust funds, and funds held on deposit, for the purchase of any such bonds or other obligations of the district and that any such bonds shall be authorized security for all public deposits. However, nothing contained in this section with regard to legal investments or security for public deposits shall be construed as relieving any such person, firm, corporation or other entity from any duty of exercising reasonable care in selecting securities.