Final answer:
In the last 40 years, there has been a notable increase in economic growth and standard of living, particularly since the 1970s. Economist Richard Easterlin has highlighted the dramatic changes in the human condition due to economic progression, suggesting a steady growth since World War II.
Step-by-step explanation:
The last 40 years have witnessed a significant increase in a particular aspect of social and economic development. Considering the time frame mentioned, the correct answer would be that there has been a marked rise in the level of economic growth. This growth has been associated with an improvement in the standard of living, and it is a subject that has become increasingly prominent in academic and public discourse since the 1970s. The economist Richard Easterlin has notably commented on the substantial changes to the human condition as a result of economic progress over the last two centuries. The increase in the standard of living implies that there has been more wealth available to various socioeconomic classes which allows for a better quality of life. The 1970s, in particular, marked new waves of immigration from Asia and Mexico which also contributed to changes in the socio-economic landscape of the United States. This question does not provide enough context to determine if the increase has been steady, episodic, or volatile. Nonetheless, the reference to Richard Easterlin suggests that overall, there has been significant progress in economic terms since World War II, corresponding with option (a) from the provided choices.