Final answer:
The criteria for market demand segmentation should be consistent and hard to change, aiding monopolistic competitors in their marketing and product strategies.
Step-by-step explanation:
For effective segmentation of market demand, the criteria used to categorize customers into groups must be consistent across consumers; hard to change. This ensures that the segments are meaningful and stable over time, allowing monopolistic competitors to effectively target their marketing efforts and product development. Segments based on difficult-to-change factors are more reliable than those based on easily changing preferences, which can lead to short-lived and less actionable market segmentation.