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

Example Input: Problem: in a class of 87 students 41 are taking french , 22 are taking german . of the students taking french or german , 9 are taking both courses . how many students are not enrolled in either course ? 
Options: a ) 6 , b ) 15 , c ) 24 , d ) 33 , e ) 54
Example Output: d

Example Input: Problem: in township k , 1 / 5 of the housing units are equiped with cable tv . if 1 / 10 of the housing units , including 1 / 4 of those that are equiped with cable tv , are equipped with videocassette recorders , what fraction of the housing units have neither cable tv nor videocassette recorders ? 
Options: a ) 3 / 4 , b ) 11 / 15 , c ) 7 / 10 , d ) 1 / 6 , e ) 2 / 15
Example Output: a

Example Input: Problem: the ratio of length of two refill is 9 : 8.2 nd refill got damaged when only half length of 2 nd refill get used . the ratio of total no . of pages written by both refill . 
Options: a ) 8 : 3 , b ) 6 : 5 , c ) 9 : 8 , d ) 9 : 4 , e ) 5 : 4
Example Output:
d