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

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: the ratio of pens to pencils is 5 to 6 . there are 5 more pencils than pens . how many pencils are there ?
Options: a ) 24 , b ) 30 , c ) 36 , d ) 42 , e ) 48
Example Output: b

Example Input: Problem: nitin ranks 15 th in a class of 47 students . what is rank from the last ?
Options: a ) 33 , b ) 38 , c ) 32 , d ) 28 , e ) 19
Example Output:
a