Comparing Quantities

For calculation of interest compounded half yearly, keeping the
principal same, which one of the following is true.
(a) Double the given annual rate and half the given number of years.
(b) Double the given annual rate as well as the given number of
years.
(c) Half the given annual rate as well as the given number of years.
(d) Half the given annual rate and double the given number of years.