Final answer:
Demand is a key component of a market economy but not the only one; both demand and supply are vital. The market revolution brought significant social and economic changes to the United States, thus the statement about demand being the only significant part is false.
Step-by-step explanation:
Understanding Market Economy
Demand is an important part of a market economy, but it is not the only significant aspect. In a market economy, both demand and supply play crucial roles. They are the primary social mechanisms for determining what is produced, how it is produced, and for whom it is produced. Furthermore, the market revolution indeed brought numerous social and economic changes to the United States, making the statement that demand is the only significant part absolutely false. Markets, exemplified by institutions like The New York Stock Exchange, function through the interaction of buyers and sellers. Economic decisions are driven by market forces in which both demand and supply come into play.
Regarding a price ceiling, it does not usually shift demand or supply directly. Instead, a price ceiling sets a legal maximum price for a good or service, which can lead to shortages when the market price would otherwise be higher. Thus, the correct answer to the question about price ceilings is (d) neither.