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

Example Input: Problem: a certain store sold pens for $ 0.35 each and pencils for $ 0.25 each . if a customer purchased both pens and pencils from the store for a total of $ 1.80 , what total number of pens and pencils did the customer purchase ? 
Options: a ) 6 , b ) 9 , c ) 10 , d ) 11 , e ) 12
Example Output: a

Example Input: Problem: a certain fruit stand sold apples for $ 0.70 each and bananas for $ 0.60 each . if a customer purchased both apples and bananas from the stand for a total of $ 6.30 , what total number of apples and bananas did the customer purchase ? 
Options: a ) 8 , b ) 9 , c ) 10 , d ) 11 , e ) 12
Example Output: c

Example Input: Problem: in what ratio must rice of rs . 32 per kg be mixed with rice of rs . 42 per kg so that cost of mixture is rs . 20 per kg ? 
Options: a ) 13 : 6 , b ) 13 : 5 , c ) 11 : 6 , d ) 11 : 5 , e ) 12 : 5
Example Output:
c