Concept:Price elasticity of supply measures how quantity supplied reacts to a change in price.Explanation:Using the price/quantity pairs (20, 100) and (16, 58):Price changes from 20 to 16, so ΔP=−4.Quantity changes from 100 to 58, so ΔQ=−42.Percentage change in price: 20−4×100=−20%.Percentage change in quantity: 100−42×100=−42%.Elasticity of supply: −20%−42%=2.1.Since 2.1>1, supply is elastic.Answer:C. Elastic supply