Sentences of a paragraph are given below in jumbled order. Arrange the sentences in the correct order to form a meaningful and coherent paragraph.
A. His role also includes the smooth flow of goods from farms and factories to the consumer.
B. As the final link between the producer and the consumer, he plays a key role in the economy.
C. It is he who promotes or impedes the sale of products.
D. The retailer determines the final cost of a product.