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

Ex Input:
Problem: a bottle contains a certain solution . in the bottled solution , the ratio of water to soap is 3 : 4 , and the ratio of soap to salt is five times this ratio . the solution is poured into an open container , and after some time , the ratio of water to soap in the open container is halved by water evaporation . at that time , what is the ratio of water to salt in the solution ? 
Options: a ) 9 : 32 , b ) 9 : 30 , c ) 32 : 9 , d ) 19 : 32 , e ) 18 : 30

Ex Output:
a


Ex Input:
Problem: an alloy is to contain steel and iron in the ratio 5 : 2 . the iron required to be melted with 35 kg of steel is ? 
Options: a ) 12 kg , b ) 14 kg , c ) 15 kg , d ) 20 kg , e ) 18 kg

Ex Output:
b


Ex Input:
Problem: if the ratio of the sum of the first 6 terms of a g . p . to the sum of the first 3 terms of the g . p . is 28 , what is the common ratio of the g . p ? 
Options: a ) 3 , b ) 1 / 3 , c ) 2 , d ) 9 , e ) 1 / 9

Ex Output:

a