The correct answer is B. In IBM decision-management tooling, Excel scenario files are a recognized mechanism for defining scenario data used to validate decision behavior through testing and simulation. The build experience for decision projects includes preparing decision logic so that it can be validated against defined input scenarios and expected outcomes. Scenario files contain input data and expected results, and users can generate Excel scenario file templates from valid rule projects or decision operations. This aligns with the exam intent: the build experience includes defining test scenarios in a business-friendly format that domain experts can understand and maintain. Option A is incorrect because JSON unit-test scenarios are not the tested activity. Option C is too generic and relates more to integration design than decision-project build validation. Option D is a development extension activity, not a normal decision build experience. Excel scenario-driven validation supports repeatable, auditable testing of decision behavior before deployment. References/topics: Decision services, testing and simulation, Excel scenario files, expected results, rule project validation, decision build validation.