Answer:
a. increases the real interest rate, which reduces private investment spending.
b. is not a major concern, because the Fed will likely lower the real interest rate when actual output is far below potential.
Step-by-step explanation:
Increase in government spending means that the government would probably have to borrow money from the credit market. Because the government is so large, it will borrow in large amounts which would force rates to rise. At these higher rates, the private sector might find it too expensive to borrow money and so would be crowed out such that they reduce their investment spending.
When the economy is facing an output that is lower than potential, the Fed will engage in monetary policy aimed at reducing interest rates to improve investment spending. This therefore negates the effect of crowing out which means that it would no longer be a major concern.