Suppose the Government Starts with a Debt of $0

Suppose the government starts with a debt of $0. Then in year 1, there is a deficit of $100 billion, in year 2 there is a deficit of $60 billion, in year 3 there is a surplus of $40 billion, and in year 4 there is a deficit of $20 billion. The government does not borrow to make interest payments. What is government debt at the end of year 4?

A) $20 billion
B) $140 billion
C) $180 billion
D) somewhat greater than $220 billion, depending on the interest rate
E) somewhat greater than $140 billion, depending on the interest rate