Answer:
A. The sum of private saving and investment is called national saving.
Explanation:
In economics the sum of private saving and investing is called the national saving, in order to calculate this you just have to calculate the nation´s income and them from that withdraw nation´s consumption, prior to taxes, that is the only correct statement fmor the options, because exports and investment have little to no correlation, and U.S investment is more often financed by privates.