In this task, you need to answer the given multiple-choice question on the general math. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Q: Problem: what is the minimum percentage increase in the mean of set f { - 4 , - 1 , 0 , 6 , 9 } if its two smallest elements are replaced with two different primes ? 
Options: a ) 25 % , b ) 50 % , c ) 75 % , d ) 100 % , e ) 200 %

A: d
****
Q: Problem: for the positive integers x , x + 2 , x + 4 , x + 7 , and x + 17 , the mean is how much greater than the median ? 
Options: a ) 0 , b ) 1 , c ) 2 , d ) 4 , e ) 7

A: c
****
Q: Problem: there has been successive increases of 25 % and then 15 % in the price of gas from the previous month . by what percentage should a driver reduce gas consumption so that the expenditure does not change ? 
Options: a ) 30 % , b ) 50 % , c ) 66.66 % , d ) 15 % , e ) 75 %

A:
a
****