Final answer:
The demand for plums is unit elastic if a percentage price change leads to an equal percentage change in quantity demanded, illustrating constant unitary elasticity with an elasticity coefficient of 1.
Step-by-step explanation:
The demand for plums is unit elastic if a given percentage change in the price of plums results in an identical percentage change in the quantity demanded for plums. This is a concept known as constant unitary elasticity, which indicates that the demand curve for plums would exhibit a unique curvature, being steeper on the higher price side and flatter as the price decreases, while demonstrating the quality that a 1% change in price would lead to a 1% change in the quantity demanded, thereby having an elasticity coefficient equal to 1.
An example of constant unitary elasticity occurs when, say, a 5% increase in the price of plums leads to an exact 5% decline in the number of plums demanded by consumers. This specific nature of the demand curve illustrates that consumers' responsiveness to price changes for plums is such that the total revenue for plums will remain unchanged with price fluctuations, as the quantity change offsets the price change.