Concept:Self service is a retail system where customers select goods on their own.
They do not need shop assistants for selection.
Payment is made at a designated checkout point.
Explanation:In self service, the customer picks items directly from shelves.
No assistant helps or attends to the customer during shopping.
The customer then pays at a checkout counter before leaving.
This practice differs from presales or after sales services.
Impulse buying is an unplanned purchase, not a service system.
Hence, the correct term is self service.
Answer:C. self service