Which of the following is accurate with regard to the public/national debt?

a. The public/national debt as a percentage of GDP has drastically increased in recent years.
b. The public/national debt as a percentage of GDP has not changed in the past decade
c. The public/national debt is a product of balanced federal budgets.
d. The public/national debt is not affected by external events such as war or a natural disaster.
e. The public/national debt has only increased under Democratic presidents.

a