The correct answer is B. Replace the current solution with two independent Validation Rules and select 'Field' as the error location. This is the answer provided in the uploaded study guide.

The usability problem is not merely that validation fails; it is that the error appears at the top of the page and requires the user to locate the affected fields manually. By associating each validation rule with the relevant field, the interface can display the error closer to the location where corrective action is required.

Separating the logic into two field-specific validation rules also makes each failure message more precise. Users can immediately identify which field is missing or invalid rather than interpreting a combined top-level error.

Option A adds explanatory help text, but help text is static and does not directly identify the field responsible for a current validation failure.

Option C misuses In-App Guidance. In-App Guidance is intended primarily for onboarding and contextual instruction rather than transactional validation.

The UX principle is that error messages should be specific, contextual, and actionable. Errors should appear as close as reasonably possible to the source of the problem so users can recover efficiently.

Study Guide reference/topics: Validation Rules, field-level errors, error recovery, Salesforce forms, Declarative Design.

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