The correct answer is: Buyer or consumer.
A buyer or consumer is the basic consuming or demanding unit of a commodity. They are the ones who purchase goods and services from sellers. Buyers can be individuals, businesses, or governments.
A seller is the one who offers goods and services for sale. They are the ones who produce or provide the goods and services that buyers demand. Sellers can be individuals, businesses, or governments.
A manufacturer is the one who produces goods. They are the ones who convert raw materials into finished products. Manufacturers can be individuals, businesses, or governments.
A producer is the one who provides services. They are the ones who perform tasks or activities for others. Producers can be individuals, businesses, or governments.
In conclusion, the basic consuming or demanding unit of a commodity is a buyer or consumer. They are the ones who purchase goods and services from sellers.