$12.$ Which one of the following bonds would generate the highest proceeds upon issuance?

a$.$ a bond with a coupon interest rate of $7\%$ and a prevailing market rate of $6\%$

b$.$ a bond with a coupon interest rate of $7\%$ and a prevailing market rate of $9\%$

c$.$ a bond with a coupon interest rate of $8\%$ and a prevailing market rate of $8\%$

d$.$ A bond with a coupon interest rate of $9\%$ and a prevailing market rate of $7\%$