In a Certain Economy, the Components of Planned Spending Are

In a certain economy, the components of planned spending are given by:  
C = 500 + 0.8 (Y - T) - 300r
I ᴾ = 200 - 400r
G = 200
NX = 10
T = 150
 
Given the information about the economy above, what would be the impact on short-run equilibrium output of a one-percentage-point increase in the real interest rate, assuming the income-expenditure multiplier equals 5?

A) Short-run equilibrium output would increase by 35 units.
B) Short-run equilibrium output would decrease by 700 units.
C) Short-run equilibrium output would decrease by 35 units.
D) Short-run equilibrium output would decrease by 7 units.