Aglobal constantis appropriate because the restricted color is expected to be reused across multiple constraint rules. Centralizing the value avoids duplicating " red " throughout the CML model and provides a single maintenance point if the business rule changes later.

For example, if the restriction eventually changes from red to another color or expands through shared logic, the administrator can modify the centralized constant instead of locating and updating multiple independent rules. This reduces inconsistency risk and follows standard configuration-engineering principles of reuse and separation of rule logic from reusable values.

Option A creates a local variable independently in every rule. That improves readability slightly but still duplicates the value and requires multiple updates. Option B is the least maintainable because it hard-codes the literal value directly in each constraint expression.

Global constants are particularly useful in large Advanced Configurator implementations where the same thresholds, product identifiers, attribute values, or policy parameters recur across many constraints.

Study Guide Reference:Configure, Price, Quote — Constraint Modeling Language; constants; reusable Advanced Configurator rule design.

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