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'.

[EX Q]: Problem: the unit digit in the product ( 891 * 781 * 912 * 463 ) is : 
Options: a ) 2 , b ) 5 , c ) 6 , d ) 8 , e ) 10
[EX A]: c

[EX Q]: Problem: ? x 24 = 173 x 240 
Options: a ) 545 , b ) 685 , c ) 865 , d ) 1730 , e ) 534
[EX A]: d

[EX Q]: Problem: find the greatest number that will divide 256 , 193 and 210 leaving 6 , 18 and 100 as remainders respectively 
Options: a ) 19 , b ) 25 , c ) 23 , d ) 20 , e ) 26
[EX A]:
b