Task: Question Answering
Input (English): Problem: machine a can finish a job in 4 hours , machine в can finish the job in 12 hours , and machine с can finish the job in 6 hours . how many hours will it take for a , b , and с together to finish the job ? 
Options: a ) 1 , b ) 2 , c ) 3 , d ) 4 , e ) 5
Output (English): b