Answer:
Demand is the consumer's ability and desire to buy goods and services.
Explanation:
The demand is when you are asking for a product.
Thus, it has to come from the buyer's/consumer's side.... not the seller's/producer's side.
The consumer demands a product, the producteur offers a product. The two other answers implicate the seller, so they are automatically eliminated.
The market establishes the price depending on the demand and offer ratio.