Aggregate demand is defined as
a. the total amount of goods and services available in the economy at all possible price levels.
b. the market value of all final goods and services produced within a country in a given period of time.
c. the total amount of goods and services in the economy that'll be purchased at all possible price levels.
d. the dollar value at current market prices of all final goods and services produced annually by factors of production owned by residents of a given