Answer: b) Aggregate demand curve
Step-by-step explanation:
The Aggregate demand curve shows the various quantities of all final commodities and services demanded at various price levels with all else being equal in an economy. It slopes downwards as a normal demand curve would because higher price commands less demand and vice versa.
It can also depict the Gross Domestic Product of a country because the GDP shows the final goods and services produced in a country whilst the AD shows the demand for those final goods and services so the money spent is the same, ceteris paribus.