What is the relationship between a nation's gross domestic product (GDP) and its standard of living?

A.
As a nation's GDP declines, its standard of living is likely to improve.
B.
As a nation's GDP declines, its standard of living is likely to stay the same.
C.
As a nation's GDP rises, its standard of living is likely to decline.
D.
As a nation's GDP rises, its standard of living is likely to improve.