The annual average rate of return can be calculated by calculating the average of three years annual return on the investment.
It is given that the investment earned a positive return of 13.1% in the first year, a negative return of -4.3% in the second year and a positive return of 5.9% in the third year.
Hence the annual average rate of return shall be (13.1-4.3+5.9)/3 = 4.9%