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

Example Input: Problem: find the ratio in which rice at rs . 7.20 a kg be mixed with rice at rs . 5.70 a kg to produce a mixture worth rs . 6.30 a kg ? 
Options: a ) 1 : 3 , b ) 2 : 3 , c ) 3 : 4 , d ) 4 : 5 , e ) none of these
Example Output: b

Example Input: Problem: x starts a business with rs . 35000 . y joins in the business after 3 months with rs . 25000 . what will be the ratio in which they should share the profit at the end of the year ? 
Options: a ) 28 : 15 , b ) 29 : 16 , c ) 25 : 23 , d ) 14 : 15 , e ) none of these
Example Output: a

Example Input: Problem: 15 different biology books and 8 different chemistry books lie on a shelf . in how many ways can a student pick 2 books of each type ? 
Options: a ) 80 , b ) 160 , c ) 720 , d ) 2100 , e ) 2940
Example Output:
e