The correct answer is a. decreases U.S. net exports and U.S. net capital outflow the same amount.
When the U.S. government runs a budget deficit, it typically borrows money to finance its spending. This increased demand for funds can lead to higher interest rates, which can attract foreign investment. As a result, while there may be an increase in capital inflow, it could manifest as a decrease in net exports since higher interest rates can make U.S. assets more attractive, leading to capital inflow and a stronger dollar. A stronger dollar makes U.S. exports more expensive for foreign buyers, thus decreasing net exports.
In summary, an increase in the budget deficit tends to lead to a decrease in both net exports and net capital outflow, as foreign investments come in, reflecting the effects of capital mobility.