Answer: C. Trade regulation
Explanation: Adam Smith is considered the father of a modern liberal economy. The modern economy pulls its roots from the "Wealth of Nation," the capital work of this economic genius. According to Smith, economic relations should be free from any government oversight, and give full freedom to entrepreneurs. In such conditions of free market, the market itself is governed by the law of capital, i.e. invisible hand. In doing so, the division of labor should be done as the key to the success of the market economy, the epochs of a narrow specialization of jobs, and thus productivity increases and the economic systems themselves are far more efficient.