Answer:
The answer is A) inter industry wage differentials
Explanation:
Although John and Mark hold equivalent secretarial jobs, their salaries are different due to that they work in different industries. The manufacturing firm might be benefiting increased effort and , lower turnover costs, a higher quality workforce, and improved worker morale and better group work norms.
Firms may find it profitable to pay greater than competitive wages to unionized workers to prevent strikes and maintain industrial peace.
