A focus group is a technique that involves organizing a discussion with a small group of stakeholders to understand their perceived value and expectations of a set of requirements and design options. A focus group can help the BA to estimate the potential value delivered by the solution, as it allows the BA to collect feedback, opinions, preferences, and attitudes from the stakeholders in a structured and interactive way. A focus group can also help the BA to identify and resolve any conflicts or issues among the stakeholders, and to build consensus and buy-in for the solution. The other options are not the best techniques for this purpose, as they are more focused on generating and evaluating ideas, collecting information from a large number of stakeholders, or interviewing stakeholders individually or in a group. References: CBAP Handbook, CBAP Study Guide, BABOK Guide