The correct answer is B) a command economy.
Based on this quote, the type of economic system is Thomas Sowell BEST referencing is a command economy.
In total opposition to a free-market economy where individuals promote capitalists ideas to invest money and create companies in order to be rich, in a command economy is the state the one who owns the means of production. The central government decides the kind of products to be produced, the price of the products, how to produce the goods, and the amount that is going to be produced.