A company is hoping to raise $10 million dollars from a debt issuance.It is considering the following option

Issue 2-year 4% convertible debentures at par on January 1, 2019. The debentures can be converted into 10 million $1 shares at maturity on December 31, 2020. Interest payments are made annually at the end of each year. Without the conversion feature, the debenture would be priced 8%

Question: where is a coupon rate and where is a market rate?