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'.

Problem: a club wants to mix 20 pounds of candy worth $ 8.00 per pound with candy worth $ 5.00 per pound to reduce the cost of the mixture to $ 6.00 per pound . how many pounds of the $ 5.00 per pound candy should be used ? 
Options: a ) 20 , b ) 30 , c ) 40 , d ) 50 , e ) 60
c

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 %
d

Problem: evaluate combination 98 c 96 = 98 ! / ( 96 ) ! ( 2 ) ! 
Options: a ) 1617 , b ) 4753 , c ) 1417 , d ) 4353 , e ) none of these

b