A corporation issues for cash $$1,000,000$ of $10\%,20-$year bonds, interest payable annually, at a time when the market rate of interest is $12\%.$ The straight$-$line method is adopted for the amortization of bond discount or premium. Which of the following statements is true?

a$.$ The amount of the annual interest expense is computed at $10\%$ of the bond cartying amount at the beginning of the year

b$.$ The bonds will be issued at a premium.

c$.$ The amount of unamortized discount decreases from its balance at $15$ suance date to a zero balance at maturity.

d$.$ The amount of the annual interest expense gradually decreases over the life of the bonds: