The Country of Hykania Does Not Trade with Any Other

The country of Hykania does not trade with any other country.Its GDP is $20 billion.Its government purchases $3 billion worth of goods and services each year,collects $3 billion in taxes,and provides $1 billion in transfer payments to households.Private saving in Hyrkania is $4 billion.What is investment in Hyrkania?

A) $1 billion
B) $2 billion
C) $3 billion
D) $4 billion