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

Q: Problem: the duplicate ratio of 3 : 4 is ? 
Options: a ) 1 : 2 , b ) 1 : 4 , c ) 1 : 8 , d ) 9 : 16 , e ) 1 : 13

A: d
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Q: Problem: what is the square root of 6,561 ? 
Options: a ) 18 , b ) 9 , c ) 45 , d ) 62 , e ) 81

A: e
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Q: Problem: the ratio between the current age of a and b is 6 : 7 . if b is 4 years old than a . what will be the ratio of the ages of a and b after 4 years ? 
Options: a ) 7 : 8 , b ) 8 : 9 , c ) 4 : 6 , d ) 4 : 8 , e ) 5 : 8

A:
a
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