Concept:As extra units are consumed, the additional satisfaction from each unit falls.Explanation:Look at the column for marginal utility: 10,5,2,1,0.Marginal utility consistently decreases as units of quantity rise.At quantity 5, total utility remains 18, while marginal utility becomes 0.This falling marginal utility with each extra unit is the law of diminishing marginal utility.So the table does not illustrate increasing returns or increasing marginal utility.Answer:C. diminishing marginal utility