The correct answer is D. Production possibility curve.
A production possibility curve (PPC) is a graph showing the maximum combinations of two goods that can be produced in an economy given the available factors of production and technology. The PPC is a useful tool for understanding the concept of opportunity cost, which is the cost of producing one good in terms of the other good that could have been produced instead.
The PPC is downward-sloping because of the law of increasing opportunity costs. This law states that as an economy produces more of one good, it must give up more and more of the other good in order to maintain the same level of efficiency. This is because the resources that are used to produce one good cannot be used to produce the other good at the same time.
The PPC is also bowed outward because of increasing returns to scale. This means that as an economy produces more of both goods, it becomes more efficient at producing them. This is because the economy can specialize in the production of each good and take advantage of economies of scale.
The PPC is a useful tool for understanding the economic choices that a country faces. It can be used to analyze the effects of changes in technology, resources, and demand. The PPC can also be used to compare the economic efficiency of different countries.