The Theory of Comparative Advantage advanced by David Ricardo in the 1800s can be summed up best by which of the following examples?

		Similar to how a consistent schedule of lifting heavy weights builds muscle mass and strength, national economies can have an advantage over other countries by regular and large investments in industry
		Economies in the northern hemisphere have a comparative advantage over economies near the equator, and economies in the southern hemisphere
		Countries collectively benefit if they each specialize in producing and trading the goods and services that they each produce most efficiently
		Free market economies have a comparative advantage over centrally planned (government planned) economies.