The production possibility frontier (PPF) is a graph that represents the maximum output combinations of two goods or services that an economy can produce given its limited resources and technology. It shows the trade-offs that an economy faces when allocating its resources between different production possibilities.

Option 1 is correct. The PPF slopes downward to the right because as an economy produces more of one good, it must give up some production of another good due to limited resources.

Option 2 is correct. The different combinations of goods and services that can be produced are represented as points on the PPF. The PPF shows the efficient use of resources in producing these combinations.

Option 3 is correct. Any point on or inside the PPF is attainable, meaning it can be achieved by efficiently allocating the existing resources and using the current technology available to the economy. Points outside the PPF are unattainable given the current resources and technology.

Option 4 is incorrect. On the PPF, the only way to increase the output of one commodity is by decreasing the output of another commodity. This is because resources are limited, and reallocating resources to one good requires sacrificing production of another good.

Alert - correct answer should be: "On the production possibility frontier, the output of one commodity