The correct answer is C. Increasing cost of sales .

ROI measures return relative to the investment required to generate that return. The study material gives the ROI logic as: “Average Return on investment = annual net income * 100/ Initial cash investment.”

If cost of sales increases , annual net income decreases, assuming selling price and sales volume do not increase enough to offset the cost increase. Lower net income reduces ROI. Increasing prices and increasing sales volume generally improve revenue and profit, while reducing inventory levels usually reduces investment tied up in assets, which can improve ROI.

Therefore, the best answer is C , because increasing cost of sales reduces profitability and therefore decreases return on investment.

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