Which of the following statements is true?

a

The ability to pay depends on income (in principle), which in turn depends on the amount of resources the person has and the price paid for those resources in the market.

b

Consumers communicate their preferences through their "dollar votes"; firms then responds to the "votes" by producing more, less, or none of the good. Later, this will be reflected in the demand for the resources employed in the production of the good.

c

The market system promotes technological progress and capital accumulation.

d

All of the above.

e

Only a) and b)