Raw materials category includes all types of farm products and natural products such as mining and mineral products, coal and iron ore. These products are usually commodities. For this reason, it is very difficult for suppliers to differentiate their products. When purchasing raw materials, the quality of the product and uninterrupted supply is important. Additionally, in order not to have any problems in production, the buyer usually keeps some stock of raw materials. Some examples of raw materials are: potatoes for a company that produces potato chips; sand for a glass producer; rye, barley and wheat for a bread producer, metallic ores for an automobile producer, etc. So, the right answer is A.