The board may issue general obligation bonds pursuant to a resolution adopted at a regular or special meeting by a majority of the total number of supervisors. Each subparagraph of section 331.441, subsection 2, paragraphs “b” and “c”, describes a separate category. Separate categories of essential county purposes and of general county purposes may be incorporated in a single notice of intention to institute proceedings for the issuance of bonds, or separate categories may be incorporated in separate notices, and after an opportunity has been provided for filing objections, or after a favorable election has been held, if required, the board may include in a single resolution and sell as a single issue of bonds, any number or combination of essential county purposes or general county purposes. If an essential county purpose is combined with a general county purpose in a single notice of intention to institute proceedings to issue bonds, then the entire issue is subject to the election requirement in section 331.442.