According to one national statistics office, this year's gross production was 60. The consumption and investment functions are respectively

C =0.5( - ) + 5, = 40 - 1000, and = 10, = 10, and = 0. The (real) equilibrium of the country in the long-run equilibrium is What is the (real) rate of interest r for this country in long-run equilibrium?

A. 1

B. 0.1

C. 0.01

D. 0.02

detailed calculation process plz.Thank you