Concept:Truck wholesalers operate from a moving vehicle and serve retailers directly.
This type of wholesaler combines selling, delivery, and cash collection in a single stop.
Explanation:A truck wholesaler loads goods, such as milk, bread, and snack foods, into a truck.
He visits retail shops and sells the items directly from the vehicle.
After making the sale, he delivers the goods to the retailer immediately.
He also collects the payment, usually in cash, at the same time.
Thus, selling, delivery, and collection are all completed in one operation.
This sets truck wholesalers apart from wholesalers who only sell or arrange delivery.
Answer:The correct option is D. truck wholesaler.