Aggregate demand is defined as

Athe total amount of goods and services available in the economy at all possible price levels.
Bthe market value of all final goods and services produced within a country in a given period of time.
Cthe total amount of goods and services in the economy that'll be purchased at all possible price levels.
Dthe dollar value at current market prices of all final goods and services produced annually by factors of production owned by residents of a given ...

Verified Answer :

The correct answer should be c. the total amount of goods and services in the economy that'll be purchased at all possible price levels.

It is very similar to A, however, aggregate demand refers to demanded goods, not all available goods, and demand seems to correspond with purchase more than it does with available.

C is the correct answer!