Task: Question Answering
Input (English): Problem: a and b can do a piece of work in 2 days , b and c in 3 days , c and a in 4 days . how long will c take to do it ? 
Options: a ) 14 days , b ) 20 days , c ) 22 days , d ) 24 days , e ) 26 days
Output (English): d