The concept of demand is best described as:_.
a. the quantity of a good or a service that people are willing and able to purchase at different possible prices.
b. the total satisfaction that consuming a good provides people at different prices.
c. the additional satisfaction derived from a quantity of goods and services obtained when income increases.
d. the quantity of a good or a service that people will offer for sale at different possible prices.
e. the quantity of a good or service that consumers will substitute when the price of a good changes.
The basic proposition of the law of demand is that:_.
a. higher prices cause buyers to demand more.
b. buyers demand lower prices.
c. higher prices cause less demand.
d. as the price of a good decreases, buyers are willing and able to purchase less.
e. as the price of a good increases, buyers are willing and able to purchase less.
In a market economy, there is relationship between the price of a good and the amount of a good that buyers are willing and able to purchase.

Explanation: The concept of demand usually deals with the consumers yearning for goods and services and the factors which determines the purchasing decision of consumers and the amount being purchased. Quantity and price are two associated variables which can be used to examine consumer behavior towards a certain product. Hence, demand for a product often refers to the quantity of product purchased or demanded by consumers based on the price of the product.

The demand proposition is simply of the notion that the number of quantity demanded for a certain product falls as the price of such product inversa and vice versa. The demand for a product decreases as its price begins to rise, leading consumers to look for substitute products which cost less.