Answer: C. retailer
Explanation:
Company D is a retailer because retailers are the ones that sell the final product and from the scenario depicted, the final product is ice cream and therefore it being sold by Company D makes them the retailer.
Tier 2 suppliers supply raw materials so that is company A. Tier 1 process raw materials so that is Company B and the manufacturer is evidently Company C which made the ice cream to be sold by D.
