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

Input: Consider Input: Problem: in what ratio must tea at rs . 62 per kg be mixed with tea at rs . 72 per kg so that the mixture must be worth rs . 64.50 per kg ? 
Options: a ) 3 : 1 , b ) 2 : 1 , c ) 5 : 2 , d ) 3 : 2 , e ) 3 : 4

Output: a


Input: Consider Input: Problem: a can contains a mixture of liquids a and b is the ratio 7 : 5 . when 3 litres of mixture are drawn off and the can is filled with b , the ratio of a and b becomes 7 : 9 . how many liter of liquid a was contained by the can initially ? 
Options: a ) 7 , b ) 10 , c ) 12 , d ) 14 , e ) 16

Output: a


Input: Consider Input: Problem: the ratio between the present ages of a and b is 5 : 3 respectively . the ratio between a ' s age 4 years ago and b ' s age 4 years hence is 1 : 1 . what is the ratio between a ' s age 4 years hence and b ' s age 4 years ago ? 
Options: a ) 3 : 9 , b ) 3 : 6 , c ) 3 : 1 , d ) 3 : 4 , e ) 3 : 2


Output: c