In the Market Clearing Model a Permanent Increase in Government

In the market clearing model a permanent increase in government purchases does not increase the real interest rate because:

A) the supply of capital services and demand for capital services increase about the same amount.
B) neither demand for capital services nor supply of capital services shift due to the permanent increase in government purchases.
C) the demand for capital services is downward sloping.
D) the supply of capital services is upward sloping.