Task: Question Answering
Input (English): Problem: a can do a piece of work in 4 hours ; b and c together can do it in 3 hours , which a and b together can do it in 2 hours . how long will c alone take to do it ? 
Options: a ) 12 hours , b ) 10 hours , c ) 6 hours , d ) 8 hours , e ) 4 hours
Output (English): a