Which of the following would cause the demand curve to shift from Demand A to Demand B in the market for oranges in the United States? a. a freeze in Florida b. a technological advance that allows oranges to ripen faster c. a decrease in the price of apples d. an announcement by the FDA that oranges prevent heart disease

The correct answer is D. An announcement by the FDA that oranges prevent heart disease

Explanation: There are a number of factors (determinants) which directly affects the level of demand for any given commodity. That is, such factors can make demand to change completely, either positively or negatively. One of such factors is the consumers’ preference or taste.

If the consumers begin to develop a preference for a particular commodity for any reason, then the demand for that commodity will go up. Like stated in the question, if there is an announcement by the government agency that oranges prevent heart disease, consumers would be more interested in eating oranges more than before. Even individuals and households that previously didn’t particularly like oranges would now be looking for them in grocery stores. The reason for this is quite simple; heart disease is a major health concern worldwide and many have died from this condition due to poor medical care. So, identifying oranges as a preventive measure would be a most welcome idea in view of the fact that it costs very little to buy oranges as a preventive measure against a killer disease and that is sure to induce consumers to develop a preference for oranges.