Answer:
disposable income; the real interest rate
Step-by-step explanation:
The consumption function is given as
C = C₀ + C₁(Yd)
Where
C₀ = autonomous consumption
C₁ = non autonomous consumption
Yd = disposable income
From the above equation, consumption is a positive function of disposable income.
The investment function is given as
I = I₀ - I₁(r)
Where
I₀ = autonomous investment
I₁ = non autonomous investment
r = interest rate
From the above equation, it can be seen that investment is a negative function of interest rate.
I hope my answer helps you