Final answer:
In a PPF diagram, the attainable and efficient points are represented on the production possibilities curve. Points outside the curve represent unattainable choices, while points inside the curve represent inefficient choices.
Step-by-step explanation:
In a PPF (Production Possibilities Frontier) diagram, the attainable and efficient points are represented on the production possibilities curve (option 1). The production possibilities curve shows the maximum combination of goods or services that can be produced given the available resources and technology. Points outside the curve (option 3) represent choices that are unattainable given the current resources, while points inside the curve (option 2) represent inefficient or wasteful choices.