Question

demand for a product is measured not only by consumer desire for a product, but also by
a opportunity costs.
b competition for the consumer.
c demand for all similar products.
d ability and willingness to buy the product.
e price elasticity

Explanation:

Demand in economics is defined as the consumer's desire, ability, and willingness to purchase a product. Opportunity costs relate to the cost of foregone alternatives, competition for the consumer and demand for similar products are related to market - level factors, and price elasticity measures the responsiveness of quantity demanded to price changes. Only ability and willingness to buy are part of the definition of demand for an individual product.

Answer:

D. ability and willingness to buy the product