An investment project is financed by loans (100%) and interest rate for the investment loans is 20%. The financial data which characterizes this project is: Initial cost = 7 000 $, Net cash-flow 1^st year = 3 200 $, Net cash-flow 2^nd year = 5 100 $ and Net cash-flow 3^rd year = 4 700 $. No residual value. The project's real payback period, computed by using the average cash-flow approach, is:

a. 2.92 years

b. 2.12 years

c. 2.79 years

d. 2.35 years

e. 2.21 years