Given the task definition, example input & output, solve the new input case.
In this task, you need to provide the correct option for a given problem from the provided options.
Example: Problem: jo ' s collection contains us , indian and british stamps . if the ratio of us to indian stamps is 6 to 2 and the ratio of indian to british stamps is 5 to 1 , what is the ratio of us to british stamps ? 
Options: a ) 5 : 1 , b ) 30 : 2 , c ) 15 : 2 , d ) 20 : 2 , e ) 25 : 2
Output: b
"u / i = 6 / 2 i / b = 5 / 1 since i is multiple of both 2 ( as per first ratio ) and 5 ( as per second ratio ) so let ' s assume that i = 10 i . e . multiplying teh first ratio by 5 and second ration by 2 in each numerator and denominator then , u : i : b = 30 : 18 : 2 i . e . u : b = 30 : 2 answer : option b"

New input case for you: Problem: a jar contains a mixture of two liquids acid ( nitric acid ) and base ( ammonium chloride ) in the ratio 4 : 1 . when 10 litres of the mixture is taken out and 10 litres of liquid base is poured into the jar , the ratio becomes 2 : 3 . how many litres of liquid acid was contained in the jar ? 
Options: a ) 14 lts , b ) 18 lts , c ) 20 lts , d ) 16 lts , e ) 26 lts
Output:
d