Final answer:
Changes in consumer preferences over the past two decades have led to decreasing demand for landlines and an increasing demand for cell phones and smartphones, as reflected by shifts in their respective demand curves. Technological advancements and demographic changes, such as an aging population, impact product demand across various sectors.
Step-by-step explanation:
As consumer tastes have shifted significantly over the past 10–20 years, there has been a marked decrease in the demand for landline phones, while the demand for cell phones and smartphones has dramatically increased. These changes in consumer tastes directly affect the demand curves for each product. When preferences move away from landlines to more advanced technology like smartphones, the demand curve for landlines shifts to the left, indicating a decrease in demand. Conversely, the increased preference for smartphones shifts their demand curve to the right, which shows an increase in demand. Factors such as technological advancements, changes in lifestyle, and upgrades in smartphone capabilities have made them essential tools for communication, banking, and accessing the internet. This is particularly evident in developing countries where smartphones have leapfrogged traditional infrastructure. The growing reliance on smartphones reflects people's evolved relationship with their phones, depending heavily on them for everyday tasks.
Changes in the composition of the population, such as the rising proportion of elderly citizens, also influence demand for various products. An aging population tends to have a higher demand for healthcare services and aids, whereas a younger population increases the demand for education and child-related services. These demographic shifts can also lead to demand changes and are represented as shifts in the demand curve.