In this task, you need to provide the correct option for a given problem from the provided options.
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Question: Problem: in assembling a bluetooth device , a factory uses one of two kinds of modules . one module costs $ 8 and the other one , that is cheaper , costs $ 3 . the factory holds a $ 100 worth stock of 25 modules . how many of the modules in the stock are of the cheaper kind ? 
Options: a ) 21 , b ) 20 , c ) 22 , d ) 23 , e ) 24

Answer: b


Question: Problem: the ratio of spinsters to cats is 2 to 7 . if there are 55 more cats than spinsters , how many spinsters are there ? 
Options: a ) 20 , b ) 21 , c ) 22 , d ) 23 , e ) 24

Answer: c


Question: Problem: the ratio between the present ages of a and b is 7 : 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 : 4 , b ) 3 : 0 , c ) 9 : 1 , d ) 9 : 2 , e ) 3 : 9

Answer:
c