The Country of Aquilonia Does Not Trade with Any Other

The country of Aquilonia does not trade with any other country.Its GDP is $30 billion.Its government purchases $5 billion worth of goods and services each year,collects $7 billion in taxes,and provides $3 billion in transfer payments to households.Private saving in Aquilonia is $5 billion.What is consumption?

A) $21 billion
B) $18 billion
C) $13 billion
D) $10 billion