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

[EX Q]: Problem: a person want to give his money of $ 5400 to his 3 children a , b , c in the ratio 2 : 3 : 4 . what is the b ' s share ? 
Options: a ) $ 2000 , b ) $ 1800 , c ) $ 2500 , d ) $ 1500 , e ) $ 1600
[EX A]: b

[EX Q]: Problem: what is the greatest positive integer r such that 3 ^ r is a factor of 9 ^ 10 ? 
Options: a ) r = 5 , b ) r = 9 , c ) r = 10 , d ) r = 20 , e ) 30
[EX A]: d

[EX Q]: Problem: sandy is younger than molly by 10 years . if their ages are in the respective ratio of 7 : 9 , how old is molly ? 
Options: a ) 27 , b ) 36 , c ) 45 , d ) 54 , e ) 63
[EX A]:
c