Let K be the number of sequences A1, A2, …, An such that n is a positive integer less than or equal to 10, each Ai is a subset of {1,2,3,…,10}, and Ai−1 is a subset of Ai for each i between 2 and n, inclusive. For example, {}, {5,7}, {2,5,7}, {2,5,7}, {2,5,6,7,9} is one such sequence, with n=5. What is the remainder when K is divided by 10?<spanclass=′latex−bold′>(A)</span>1<spanclass=′latex−bold′>(B)</span>3<spanclass=′latex−bold′>(C)</span>5<spanclass=′latex−bold′>(D)</span>7<spanclass=′latex−bold′>(E)</span>9