A can do a piece of work in 4 hours; B and C together can do it in 3 hours, which A and C together can do it in 2 hours. How long will B alone take to do it?	Choose the correct choice from the following answers.
A) 1/19 B) 1/11 C) 1/12 D) 1/17 E) 1/14
A's 1 hour work = 1/4;   (B + C)'s 1 hour work = 1/3;   (A + C)'s 1 hour work = 1/2   (A + B + C)'s 1 hour work = (1/4 + 1/3) = 7/12   B's 1 hour work = (7/12 + 1/2) = 1/12   B alone will take 12 hours to do the work.   Answer: 1/12
<result>C</result>
A can do a piece of work in 4 hours; B and C together can do it in 3 hours, which A and C together can do it in 2 hours. How long will B alone take to do it?