Task: Question Answering
Input (English): Problem: a can do a piece of work in 6 hours ; b and c together can do it in 4 hours , which a and c together can do it in 3 hours . how long will b alone take to do it ? 
Options: a ) 8 hours , b ) 6 hours , c ) 14 hours , d ) 12 hours , e ) 5 hours
Output (English): d