suppose that the currenr one year rate (one year spot rate) as expected one year T bill rates over the following three years (i.e years 2,3,4 respectivly) are as follows

1R1=4.05%, E(2R1)=5.05% E(3R1)=5.55% E(4R1)=5.90%

using unbiased expectations theory, what is the current (long term) rate for four year maturity treasure securities?

a. 5.9000%

b. 5.1375%

c. 1.4430%

d. 5.1352%