Answer:
c. not affect the bond's duration.
Step-by-step explanation:
The bond duration measures the sensitivity of a bond's price to change in the interest rate. It is a linear measure of those years in which the repayment of the principal is due. the change in interest rate does not affect the duration of the bond.
On the other hand decrease in interest rate would increase the bond's PV and Price of the bond as well.
Payment frequency would not change with the decrease interest rate.
The Coupon rate will also remain the same whether the interest rate increases or decreases.