Other Things Equal, an Increase of Treasury Bonds from $100

$$\begin{array} { | l | c | } \hline \text { Security } & \text { Amount (in Billions) } \\\hline \text { Treasury Bills } & \$ 220 \\\hline \text { Corporate Bonds } & 140 \\\hline \text { Treasury Notes } & 80 \\\hline \text { Corporate Stock } & 200 \\\hline \text { US Savings Bonds } & 60 \\\hline \text { Treasury Bonds } & 100 \\\hline\end{array}$$ Other things equal, an increase of Treasury bonds from $100 billion to $120 billion in the economy would

A) not change the size of the public debt.
B) increase the public debt from $460 billion to $480 billion.
C) increase the public debt from $400 billion to $420 billion.
D) decrease the public debt by $20 billion.