if an automobile dealer sells a service contract that ranges 12-36 months, which of the following increases, service revenue or deferred service revenue? contract stipulates that the dealer will cover specific repairs on covered vehicles.

Becker's says "only" deferred service revenue will be covered - is this because I cannot assume that the dealer is selling an ongoing number of these contracts and has an idea of the % of the work they will complete in a period?

thanks!