A public sector agency has implemented Public Sector Solutions for managing their Grants program.

When an applicant's eligibility for a grant program is declined, and the decision needs to be reviewed or explained within Salesforce Public Sector Solutions, the appropriate tool to use is the Decision Explainer (Option B). This functionality is part of Salesforce's intelligent decision-making tools that provide insights into how decisions were derived based on the configured criteria and data inputs. The Decision Explainer allows administrators or authorized users to review the decision-making process in detail, identifying exactly why an application was declined based on eligibility or other criteria.

Other options like using Salesforce debug logs (Option A) or testing with relevant data sets (Option C) are less direct and can be more time-consuming without providing the specific, user-friendly explanations that the Decision Explainer offers. The Selection Explainer (Option D) is not specifically a standard Salesforce tool under this name, making Option B the most accurate and relevant choice.