The best approach is to create realistic user personas based on the gathered user data (B). The ITIL 4 Specialist: Create, Deliver and Support documentation (Section 3.1.3) states: "User personas, developed from data-driven insights, provide a focused representation of target users, enabling tailored design that aligns with their needs and circumstances." This method ensures practicality without overwhelming the process, unlike option A's broad involvement. Option C is a data-gathering step; option D prioritizes technology over user needs. The guide notes: "Personas enhance service design by guiding decisions throughout the value stream." Reference: ITIL 4 Specialist: Create, Deliver and Support, Section 3.1.3 - User Personas in Service Design.