A．Supply and demand.B．Laissez faire.C．Self-interest.D．N……

TEXT C
Adam Smith, the Scottish professor of moral philosophy, was thrilled by his recognition of order in the economic system. His book, The Wealth of Nations (1776), is the germinal book in the field of economics which earned him the title, the father of economics.
In Smith’s view, a nation’s wealth was dependent upon production, not agriculture alone. How much it produced, he believed, depended upon how well it combined labour and the other factors of production. The more efficient the combination, the greater the output, and the greater the nation’s wealth.
The essence of Smith’s economic philosophy was his belief that an economy would work best if left to function on its own without government regulation. In those circumstances, self-interest would lead business firms to produce only those products that consumers wanted, and to produce them at the lowest possible cost. They would do this, not as a means of benefiting society, but in an effort to outperform their competitors and gain the greatest profit. But all this self-interest would benefit society as a whole by providing it with more and better goods and services, at the lowest prices.
Smith said in his book: "Every individual endeavours to employ his capital so that its produce may be of greatest value. He generally neither intends to promote the public interest, nor knows how much he is promoting it. He intends only his own security, only his own gain. And he is in this led by an ’invisible hand’ to promote that which was no part of his intention. By pursuing his own interest he frequently promotes that of society more effectually than when he really intends to promote."
The "invisible hand" was Smith’s name for the economic forces that we today would call supply and demand, Smith agreed with the physiocrats and their policy of "laissez faire", letting individuals and businesses function without interference from government regulation. In that way the "invisible hand" would be free to guide the economy and maximize production.
Smith was very critical of monopolies which restricted the competition that he saw as vital for economic prosperity. He recognized that the virtues of the market mechanism are fully realized only when the checks and balances of perfect competition are present. Perfect competition refers to a market in which no firm or consumer is large enough to affect the market price. The "invisible hand" theory is about economies in which all the markets are perfectly competitive. In such circumstances, markets will produce an efficient allocation of resources, so that an economy is on its production-possibility frontier. When all industries are subject to the checks and balances of perfect competition, markets can produce an efficient bundle of products with the most efficient techniques and using the minimum amount of inputs. But when monopolies become pervasive, the remarkable efficiency properties of the invisible hand may be destroyed.
What does the "invisible hand" refer to

A．Supply and demand.
B．Laissez faire.
C．Self-interest.
D．Non-interference from the government.