A set of 10 new questions in each round. Question: ( 1 of 10 ) If William can finish the work in 12 days and Matthew can finish the same work in 16 days, then in how many days both can finish the work together? (A) 6 6/7 days or 6.857 days (B) 14 days (C) 12 6/7 days or 12.857 days (D) 28 days