Sam Seel has a small portfolio of options. Since the options are currently in-the-money, he is considering the possibility of early exercise. Which of the following statements is correct?

a.        It is never optimal to exercise European call options early.

b.        It is best to exercise a put option when it is just in-the-money.

c.        Early exercise of put options becomes more attractive when  interest rates rise.

d.        Early exercise of put options becomes more attractive when  interest rates decline.

the answer is C