Final answer:
Loyal customers most commonly engage in instrumental complaint behavior, seeking practical solutions to issues with a product or service.
Step-by-step explanation:
Loyal customers are more likely to engage in instrumental complaint behavior. Instrumental complaints are those where the customer expects a practical outcome or solution to their problem. These customers are typically invested in the relationship with the company and believe in the product or service, thus they wish to see a situation resolved rather than just to vent their dissatisfaction. This is in contrast to expressive complaints, which are more about airing grievances, passive complaints, where a customer might feel discontent but not express it, and active complaints, which could include sharing negative experiences with others or seeking a resolution.