Either Worker A or Worker B will produce $20,000 of output for Employer X (who only needs one worker). Worker A could produce $12,000 worth of goods elsewhere (this is Worker A's best alternative); Worker B could produce $15,000 worth of goods elsewhere (this is Worker B's best alternative). Which of the following (if they occur) is not Pareto Efficient in the sense that gainers cannot compensate losers for their losses?

A) Employer X hires Worker A for $14,000.
B) Employer X hires Worker A for $18,000.
C) Employer X hires Worker A for $5,000.
D) Employer X hires Worker B for $18,000.

Pareto efficiency simply means that the resources uses in an economy are allocated in the most economically efficient manner. In such scenario, no change can be made without having to make someone worse off.

Based on the information, it'll not be Pareto efficient if Employer X hires Worker B for $18,000 since Worker B could produce $15,000 worth of goods elsewhere compared to worker A who can produce $12000 worth of goods.