What are the two variables whose relationship is given by the environmental Kuznets curve?

Environmental degradation and per capita income

The correct answer is Option (4) - Environmental degradation and per capita income

The relationship described by the Environmental Kuznets Curve (EKC) is between environmental degradation and per capita income. It suggests that environmental degradation initially increases with economic growth (as income levels rise), but after reaching a certain income threshold, environmental degradation begins to decrease as societies prioritize environmental conservation and adopt cleaner technologies.