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

Example Input: Problem: the ratio of toddlers to infants at a day care center is 7 to 3 . if 12 more infants join the day care to change the ratio to 7 to 5 , how many toddlers are there at this day care center ? 
Options: a ) 24 , b ) 36 , c ) 42 , d ) 72 , e ) 120
Example Output: c

Example Input: Problem: an alloy is to contain steel and iron in the ratio 5 : 2 . the iron required to be melted with 35 kg of steel is ? 
Options: a ) 12 kg , b ) 14 kg , c ) 15 kg , d ) 20 kg , e ) 18 kg
Example Output: b

Example Input: Problem: in a zoo , the ratio of the number of cheetahs to the number of pandas is 1 : 3 and was the same 5 years ago . if the increase in the number of cheetahs in the zoo since then is 2 , then what is the increase in the number of pandas ? 
Options: a ) 2 , b ) 3 , c ) 5 , d ) 6 , e ) 15
Example Output:
d