Task: Question Answering
Input (English): Problem: a single reservoir supplies the petrol to the whole city , while the reservoir is fed by a single pipeline filling the reservoir with the stream of uniform volume . when the reservoir is full and if 40,000 liters of petrol is used daily , the suply fails in 90 days . if 32,000 liters of petrol is used daily , it fails in 60 days . how much petrol can be used daily with out the supply ever failing ? 
Options: ['a ) 64000 liters', 'b ) 56000 liters', 'c ) 78000 liters', 'd ) 60000 liters', 'e ) none of these']
Output (English): b