Task: Question Answering
Input (English): Problem: in a manufacturing plant , it takes 36 machines 4 hours of continuous work to fill 4 standard orders . at this rate , how many hours of continuous work by 72 machines are required to fill 12 standard orders ? 
Options: a ) 3 , b ) 6 , c ) 8 , d ) 9 , e ) 12
Output (English): b