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

Example Input: Problem: teas worth rs . 126 per kg and rs . 135 per kg are mixed with a third variety in the ratio 1 : 1 : 2 . if the mixture is worth rs 156 per kg , the price of the third variety per kg will be ? 
Options: a ) rs . 147.50 , b ) rs . 785.50 , c ) rs . 178.50 , d ) rs . 258.50 , e ) none of these
Example Output: c

Example Input: Problem: a pet store holds cats and dogs . if the difference between the number of cats and the number of dogs is 3 . what could be the ratio of cats to dogs in the pet store ? 
Options: a ) 12 : 15 , b ) 1 : 4 , c ) 1 : 5 , d ) 2 : 5 , e ) 1 : 3
Example Output: a

Example Input: Problem: a survey was taken among 100 brainiacs . of those surveyed , twice as many brainiacs likerebus teasers as math teasers . if 18 brainiacs like both rebus teasers and math teasers and 4 like neither kind of teaser , how many brainiacs like math teasers but not rebus teasers ? 
Options: a ) 17 , b ) 18 , c ) 19 , d ) 20 , e ) 21
Example Output:
d