Consider the following data on a proposed investment:

-Investment required: R 160,000

-Annual cash inflows: R 40,000

-Life of the investment: 6 years

-Salvage value: 0

Cost of capital: 10%

Based on the above data, what is the payback period of the proposed investment project?

a) 0.25 years

b) 3 years

c) 4 years

d) 5 years