We have 31 pieces where 1 is written on two of them, 2 is written on eight of them, 3 is written on twelve of them, 4 is written on four of them, and 5 is written on five of them. We place 30 of them into a 5×6 chessboard such that the sum of numbers on any row is equal to a fixed number and the sum of numbers on any column is equal to a fixed number. What is the number written on the piece which is not placed?<spanclass=′latex−bold′>(A)</span>1<spanclass=′latex−bold′>(B)</span>2<spanclass=′latex−bold′>(C)</span>3<spanclass=′latex−bold′>(D)</span>4<spanclass=′latex−bold′>(E)</span>5