Concept:The production possibility frontier (PPF) illustrates the maximum output combinations an economy can produce; its shape depends on how opportunity cost behaves.
Explanation:The PPF is typically bowed outward, indicating that producing extra units of one good requires giving up increasingly more of the other good.
This increase in opportunity cost occurs because resources are not equally suitable for producing all goods.
When workers or land are shifted from one output to another, their productivity falls, reflecting the law of diminishing returns.
The law of diminishing returns—also called the law of variable proportions—states that adding one factor of production while holding others constant yields progressively smaller increases in output.
As a result, the PPF is concave to the origin.
Technology only shifts or rotates the frontier, while the list of factors merely sets the limits, not the curvature.
Therefore, the shape of the PPF is directly determined by diminishing returns.
Answer:B. law of diminishing returns