Why are entity services often designed before other types of services?

A: entity services are business-centric and the design of business logic is considered to have priority over other types of service logic B: entity services can be designed more independently, primarily because they are expected to be generic and reusable and because their functional contexts are derived from existing business entity models C: entity services provide the least reusable logic and therefore require the most up-front attention D: entity services cannot be designed prior to other types of services