Any municipality adopting a council-manager plan of government shall provide in its charter either:
a. That the council members shall be elected at large by the voters of the municipality at the regular municipal election, on general election, as the charter shall provide; or
b. That the municipality shall be divided into wards pursuant to the authority granted in section 1-13 or 1-19 (C.40:69A-13 or 40:69A-19), that council members shall be elected at large and by wards at the regular municipal election or general election, as the charter shall provide; and that no more than one council member shall be elected from each ward established in the municipality, and all other council members shall be elected at large.