Failure to notify the department under section 2422 is considered an exercise of the option in section 2422(c). Selection of the option in section 2422(a) or (b) does not preclude the selection of the option in section 2422(c) and the implementation of section 2424 at a later time. During the transition period, a city exercising the option in section 2422(c) shall continue local financial support for affected services at a level considered by the department to be consistent with support previously provided by the city, or with the requirements of the approved plan.