Final answer:
The level of private saving in the economy is $1 trillion.
Step-by-step explanation:
The level of private saving in the economy can be calculated by subtracting consumption (C) and taxes (T) from income (Y). Private saving (S) = Y - C - T. Based on the given information, we can calculate:
S = 12 trillion - 8 trillion - 3 trillion = 1 trillion
Therefore, the level of private saving in the economy is $1 trillion. None of the answer choices provided match this amount, so it seems that none of the options given accurately represent the level of private saving.