A clean build puts the rule where Salesforce evaluates it. Roll-up summary fields calculate values from child detail records and store the result on the master. The relationship type and field type decide whether the calculation is available declaratively. Choose A. Roll-up summaries are limited to master-detail relationships.; C). An object can have 25 roll-up summaries. This is the option that best matches the Salesforce responsibility being tested under Data Modeling and Management.
A practical administrator would confirm the object context, the user action, and whether the result must be stored, calculated, displayed, automated, approved, or deployed. Here the selected answer is the one that acts at the correct point in that chain. It keeps the configuration declarative and avoids inventing a process around a problem that Salesforce already has a native feature to solve.
The remaining answers do not control the same Salesforce behavior. B (Roll-up summaries allow MAX, MIN, SUM, COUNT, and AVG.) does not fit cleanly; it solves a symptom of the problem rather than the Salesforce mechanism that owns the result. D (An object can have 20 object references.) misses the mark because it addresses a neighboring feature area rather than the exact behavior requested. The result is a cleaner app design because the behavior is handled by the feature Salesforce built for that purpose.
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