Final answer:
The invalid Commerce rule type is Recommendation rule.
Step-by-step explanation:
The invalid Commerce rule type is Recommendation rule. Constraint rule, Hiding rule, and Validation rule are all valid Commerce rule types.
Which is an invalid Commerce rule type? Among the options provided, C. Hiding rule is not a standard commerce rule type used in defining business logic for commercial systems or e-commerce platforms.
Constraint rules are used to limit product configuration options based on rules defined for compatibility or customer requirements. Recommendation rules suggest products or services to customers based on their selection criteria. Validation rules ensure that the data entered by users meets certain criteria before being accepted by the system.
Therefore, a Hiding rule does not fit within the typical e-commerce rule classification and can be considered an invalid Commerce rule type within this context.