A clean build puts the rule where Salesforce evaluates it. Choose A. TODAY(). In Salesforce terms, this is a formula logic issue. Formula and validation expressions must respect Salesforce data types. Picklists require picklist-aware handling, dates require date functions or date arithmetic, and image or text formulas must return the correct type.
The selected configuration is the professional answer because it is native, declarative, and placed at the right scope. If the requirement later expands, another administrator can inspect the same metadata area and understand how the behavior is being produced. That is far better than a solution that depends on hidden assumptions or user training.
The remaining answers do not control the same Salesforce behavior. B (DATEVALUE()) does not fit cleanly; it solves a symptom of the problem rather than the Salesforce mechanism that owns the result. C (NOW()) is only a partial match because it does not provide the same direct administrative control as the selected option.
D (DATETIMEVALUE()) 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.
For formulas, data type conversion is critical. TEXT, ISPICKVAL, DATEVALUE, TODAY, NOW, IMAGE, CASE, and LEFT solve different expression problems and cannot be swapped casually.
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