The council may, and upon petition therefor signed by voters equal in number to at least 15 percent of the electors voting at the last previous city election, shall, submit to the voters at a regular or special election the question of adoption by the city of Optional Plan A or B. Only one plan shall be so submitted at any one election, except that any such plan shall be submitted at the election on incorporation of a city if the incorporation petition so requests and the population of the proposed city, when the submission of Optional Plan B is proposed, is more than 1,000. No plan, except a home rule charter submitted under chapter 410, shall be submitted in any city in which another optional plan is already in effect until the latter plan has been in effect for at least three years.
The proposals for the adoption of optional plans shall be stated on the ballot substantially as follows:
"Shall Optional Plan A, modifying the standard plan of city government by providing for the appointment by the council of the clerk and treasurer be adopted for the government of the city?"
"Shall Optional Plan B, providing for the council-manager form of city government, be adopted for the government of the city?"
If the city has combined the offices of clerk and treasurer, the word "clerk-treasurer" shall be substituted for the words "clerk and treasurer" in the question on the ballot on adoption of Optional Plan A. In any of these cases, the question shall be followed by the words, "Yes" and "No" with an appropriate square before each in which a voter may record a choice.
If a majority of the votes cast on the question of adoption of Optional Plan A or B is in the affirmative, the plan so voted upon shall be adopted in the city and, once placed in effect as subsequently provided in this chapter, shall remain in effect until abandoned by a similar majority at subsequent election at which the question of abandonment or adoption of another optional plan is submitted.
At any time more than three years after the adoption of an optional plan in a city, the question of abandonment of such plan may be submitted to the voters, in the same manner as provided in the foregoing sections for the submission of the question of adoption, except that in the statement of the question on the ballot, the word "abandoned" shall be substituted for the word "adopted." If a majority of the votes cast on the question is in favor of abandonment, the plan shall be abandoned; and, subject to the special provisions for transition back to the standard form of government contained in subsequent sections of this chapter, the standard plan of government shall be resumed in the city and all the provisions of law applicable to cities in which an optional plan is not in operation shall henceforth apply to the city.
Whenever the question of adoption or abandonment of an optional plan is submitted in any city and results in a majority vote in favor of the question submitted, the clerk shall promptly file with the county auditor and with the secretary of state a certificate stating the date of election, the question submitted, and the vote on the question.