If "the" multiplier is 6, the income multiplier with respect to the money supply is 4, and the money multiplier is 5, then which of the following policies increase income by $50 billion dollars?
a. Increase money supply by $2.5 billion.
b. Increase in government spending by $10 billion.
c. Fed purchase of $12.5 billion in bonds.
d. Increase in government spending by $3 billion and the money supply by $8 billion.
e. Fed sale of $2 billion in bonds and increase in government spending by $15 billion.
f. Fed purchase of $1 billion in bonds and increase government spending by $5 billion.