Answer: 4.4%
Explanation;
Using the liquidity premium theory, the interest rate on the bond would be the average of one-year interest rates up to the year of interest plus the liquidity premium in the year of interest.
Interest on four-year bond = Average of one year rates up to Year 4 + Year 4 liquidity
= (( 2 + 2.5 + 3.2 + 3.9)/4) + 1.5
= 2.9 + 1.5
= 4.4%