Which of the following reasons might explain why an economy would be operating inside its production possibilities curve (PPC)?
A. Because shrinking population has reduced the number of productive workers in the economy. B. Because technological innovations have increased the productivity of labor and capital. C. Because damage to natural resources, such as might be caused by deforestation leading to erosion of topsoil, has shrunk the land resource. D. Because of unemployment or underemployment of labor, perhaps due to discrimination against employing workers of a certain race or gender.