Final answer:
The final stage of economic development according to Walt Rostow is the 'Age of high mass consumption.' This stage is characterized by a high standard of living, consumerism, advanced technology, and a complex industry.
Step-by-step explanation:
According to Walt Rostow's model of economic development, the final stage is the 'Age of high mass consumption.' This stage represents a society that has achieved a high standard of living, with a focus on consumerism and a smaller family size. In this stage, the population growth rates have slowed down, and the country has advanced technology and a complex industry.