Which of following state is correct?

Question $12$Answer

a$.$

The duration of a coupon$-$paying Treasury bond would increase if its term to maturity increases.

b$.$

The duration of a coupon$-$paying Treasury bond would increase if its coupon rate increases.

c$.$

The duration of zero$-$coupon bond would increase if its yield to maturity decreases.

d$.$

None of above statement is correct.