The Percentage of the Population in the Two Higher Income

The percentage of the population in the two higher income classes (defined by Pew as having more than 200% of median family income) declined from more than 60% in the 1970s to 50% in 2015. Economists that see the decline in the middle class as a consequence of declining growth argue

A) The middle class is responsible for buying a high portion of the goods and services produced.
B) If the poor can't afford goods, fewer will be produced.
C) The middle class is responsible for most of the investment dollars available
D) That middle class are generated by growth and without it, there are fewer such jobs.