Twelve couples are seated around a circular table such that all of men are seated side by side, and every women are seated to opposite of her husband. In every step, a woman and a man next to her are swapping. What is the least possible number of swapping until all couples are seated side by side?<spanclass=′latex−bold′>(A)</span>36<spanclass=′latex−bold′>(B)</span>55<spanclass=′latex−bold′>(C)</span>60<spanclass=′latex−bold′>(D)</span>66<spanclass=′latex−bold′>(E)</span>None