TheScrum Guidedefines the Product Owner as "accountable for maximizing the value of the product resulting from the work of the Scrum Team." Option B (Value optimizer) encapsulates this core focus on value delivery. Option A (Requirements engineer) is too narrow-while they manage requirements, their role transcends engineering to strategic vision. Option C (Team manager) is incorrect-they don't manage the team; the Scrum Master supports team self-management. Option D (Go-between) understates their authority; they actively shape the product, not just relay information. Thus, B is the best description.