Explanation
A business case is a document that provides the justification for initiating a change initiative, such as a project or a program. It describes the business need, the expected benefits, the costs, the risks, and the alternatives of the proposed solution. A business case is usually the first deliverable that a team of BAs produces to present to management for approval. It helps to secure the support and resources needed for the change initiative, and to align it with the strategic objectives of the organization. The other options are not the first steps that the team should do, as they are more relevant for later stages of the business analysis process, such as planning, analysis, and design. References: CBAP Handbook, CBAP Study Guide, BABOK Guide