Answer:
The correct answer is: We should strive to push the PPF outward.
Explanation:
A normative statement is the kind of statement that says 'what should be'. A positive statement on the other hand states 'what is', 'what was' or 'what would be'.
In the given choices all the statements other than the last one are positive. They are stating 'what is'.
The last statement says 'what should be or what ought to be'. It is based on opinion and value judgments instead of facts and figures.