Comprehensive and Detailed Explanation From documents:

In TOGAF, a Business Scenario is an ADM technique used to capture and structure business requirements in a way that directly informs the development and validation of architectures. It frames a specific business problem (or opportunity) and articulates the desired outcomes/objectives, along with the business and technical context, the involved actors and roles (human and system), and the measures of success. This makes option A correct because it concisely captures the essence of a Business Scenario: a well-defined business problem coupled with the outcomes the business seeks to achieve.

A good Business Scenario typically includes:

The business problem/opportunity and drivers.

The business and technical environment/context in which the problem exists.

The desired outcomes/objectives and measures of success (how success will be recognized).

Actors and roles (both human and system) and their interactions.

Capabilities and high-level requirements implied by the scenario.

Business Scenarios are especially valuable in Phase A: Architecture Vision to validate scope, objectives, and business value, and they continue to be used throughout Phases B–D to test and validate the target architectures and to maintain requirements traceability via Requirements Management. They promote shared understanding among stakeholders and provide a concrete basis for evaluating solution options and assessing architecture fitness-for-purpose.

Why the other options are incorrect:

B. A use-case for developing a business model. While Business Scenarios and use-cases are related, a Business Scenario is broader. It provides context, problem, objectives, and measures of success; use-cases are often derived from or complement Business Scenarios to specify interactions, but a Business Scenario is not merely a use-case.

C. A method to quantify readiness for change. This describes Business Transformation Readiness Assessment, a separate TOGAF technique used to gauge an organization’s readiness to execute change. It is not what TOGAF defines as a Business Scenario.

D. A technique to identify differences between a baseline and a target architecture. That is Gap Analysis, another distinct ADM technique used to determine what needs to change to move from the current state to the desired future state.

References (official TOGAF materials; no links):

The Open Group, TOGAF® Standard, Version 9.2, Part III: ADM Guidelines & Techniques — Business Scenarios; also Requirements Management, and Phase A: Architecture Vision (Part II) for where Business Scenarios are applied.

The Open Group, TOGAF® Series Guide: Business Scenarios — definition, structure, and usage of Business Scenarios across the ADM.

The Open Group, TOGAF® 9 Foundation Study Guide (latest edition) — coverage of Business Scenarios as an ADM technique and their relationship to use-cases.

The Open Group, TOGAF® 9 Certified Study Guide (latest edition) — contrasts with related techniques (Gap Analysis; Business Transformation Readiness Assessment) and explains use within Phase A and Requirements Management.===========