In this task, you need to provide the correct option for a given problem from the provided options.

Example Input: Problem: the marks obtained by polly and sandy are in the ratio 4 : 5 and those obtained by sandy and willy are in the ratio of 5 : 2 . the marks obtained by polly and willy are in the ratio of . . . ? 
Options: a ) 2 : 1 , b ) 3 : 2 , c ) 4 : 3 , d ) 5 : 4 , e ) 6 : 5
Example Output: a

Example Input: Problem: the hcf of two numbers is 42 and the other two factors of their lcm are 10 and 20 . what is the largest number . 
Options: a ) 462 , b ) 450 , c ) 840 , d ) 504 , e ) 555
Example Output: c

Example Input: Problem: two vessels p and q contain 62.5 % and 87.5 % of alcohol respectively . if 4 litres from vessel p is mixed with 4 litres from vessel q , the ratio of alcohol and water in the resulting mixture is ? 
Options: a ) 1 : 2 , b ) 1 : 3 , c ) 3 : 1 , d ) 1 : 5 , e ) 1 : 4
Example Output:
c