Which of the following illustrates diminishing marginal returns ? A. Total cost decreases as the quantity of labor hired increases. B. Hiring more workers decreases the productivity of each additional worker. C. Debra produces 30 hats per hour. D. A company makes greater investments as it earns higher profits.

The correct option is B, hiring more workers decreases the productivity of each additional worker.

Explanation:

The law of decreasing returns states "As a firm uses more of a variable input, with a given quantity of fixed inputs, the marginal product of the variable input eventually decreases"

Option A shows an increasing returns to scale and not diminishing marginal returns.

Option C only tells us output per hour without any correlation to any other variable in order to decide if the number of output per hour is the same, below or above the expected output per hour

Option D, shows the need to make further investment to earn more investment returns