Answer:
D. John Keynes
Step-by-step explanation:
The quote by John Keynes is stating that throughout history, there have been periods of ups and downs, but overall the standard of living for the average person has not changed significantly over the course of four thousand years. There have been some periods where the standard of living has improved, but these improvements have only been incremental, not revolutionary. While there have been times of great prosperity and times of great hardship, the average person's standard of living has not changed dramatically over time. This quote reflects Keynes' view that economic growth is not necessarily a linear process and that there are many factors that can influence a society's economic development over time.