using the unbiased expectations theory what is the current long term rate for four year maturity treasury securities 5%

Suppose that the current one-year rate (one-year spot rate) and expected one-year T-bill lates over the following three years (i.e, years 2, 3, and 4, respectively) are as follows: 23 iR1 500. E(2N).. 5.5%. EGri)-6.500 E(3M)-6.5% E(4,1) Earl) 7.00 o 7.000 Using the unbiased expectations theory, what is the current (long-term) rate for four-year-maturity Treasury securities? a 6.00 percent b 6.33 percent c 6.75 percent d 7.00 percent