A. By the "immediate payment plan" is meant that the entire assessment against any and all parcels of land assessed shall mature to be paid at or before delinquency in a single payment for the entire assessment for each parcel assessed.

B. By the "bond installment plan" is meant a division of the entire assessment against any parcel of land into equal annual installments, not to exceed ten annual installments, one such installment with interest to mature and become payable each year and the issuance by the city of improvement district installment bonds to be paid exclusively from funds derived from the assessments levied in the local improvement districts covered by such bonds.

C. The failure of the city council or other legislative body to designate in the resolution of its intention to improve, or in the ordinance creating an improvement district, the mode of payment of the assessment, shall be construed to mean that the assessment in such improvement district shall be payable upon the "immediate payment plan." The city council shall have the power at any time prior to the equalization of the assessment roll in any improvement district and prior to the issuance of any improvement district fund warrants, to change the mode of payment in such district from the "immediate payment plan" to the "bond installment plan."