The Accompanying Table Gives Budget Information for a Hypothetical Economy

$$\begin{array} { | c | c | c | c | } \hline & \begin{array} { c } \text { Government } \\\text { Spending }\end{array} & \text { Tax Revenues } & \text { GDP } \\\hline \text { Year 1 } & \$ 450 & \$ 425 & \$ 2,000 \\\hline \text { Year 2 } & 500 & 450 & 3,000 \\\hline \text { Year 3 } & 600 & 500 & 4,000 \\\hline \text { Year 4 } & 640 & 620 & 5,000 \\\hline \text { Year 5 } & 680 & 580 & 4,800 \\\hline \text { Year 6 } & 600 & 620 & 5,000 \\\hline\end{array}$$ The accompanying table gives budget information for a hypothetical economy. Assume that all budget surpluses are used to pay down the public debt. If year 1 is the ?rst year of this nation's existence and
Year 6 is the present year, this nation's public debt is

A) $275 billion.
B) $100 billion.
C) $3,540 billion.
D) $230 billion.