Final answer:
Economists are referring to the entire demand curve or schedule when they speak of Demand in a particular market, representing the relationship between different prices and quantities demanded. The correct option is 1.
Step-by-step explanation:
When economists speak of Demand in a particular market, they are referring to the overall relationship between the price of an item and the quantity of that item that buyers are willing and able to purchase at each price. This concept is illustrated by a demand curve or a demand schedule. Demand is based on consumer needs and wants in combination with their ability to pay. In contrast, quantity demanded refers to the amount of an item that consumers are willing to buy at a specific price, which is just one point on the demand curve, representing one price-quantity combination on the demand schedule. Therefore, when addressing the original question, economists are referring to the entire demand curve or schedule.
In economic terminology, demand is not the same as quantity demanded. When economists talk about demand, they mean the relationship between a range of prices and the quantities demanded at those prices, as illustrated by a demand curve or a demand schedule. When economists talk about quantity demanded, they mean only a certain point on the demand curve, or one quantity on the demand schedule. In short, demand refers to the curve and quantity demanded refers to a (specific) point on the curve.