A clean build puts the rule where Salesforce evaluates it. Lightning App Builder controls page composition, component visibility, activation, assignments, and specialized surfaces such as record pages, home pages, action regions, activity surfaces, and utility bars. The correct response is therefore D. Create a custom action.
The scenario is not asking for a feature list. It is asking which configuration produces the requested result with the fewest moving parts. A Salesforce app builder should favor a standard, visible Setup configuration whenever it fully meets the business need. That approach makes the build easier to validate in sandbox and easier to explain during release review.
The remaining answers do not control the same Salesforce behavior. A (Customize a Global Quick Action) would be fragile here because Actions improve user entry, but they are not a substitute for relationship modeling, reporting logic, or back-end automation. B (Add Path on Account hierarchy) does not fit cleanly; it solves a symptom of the problem rather than the Salesforce mechanism that owns the result. C (Add a custom link on Account) is only a partial match because it does not provide the same direct administrative control as the selected option. The result is a cleaner app design because the behavior is handled by the feature Salesforce built for that purpose.
---