The correct choice is (d) The Web page has multiple versions for searching blocks by an EM algorithm
The best explanation: The Web page for two versions of MEME, ParaMEME, a Web program that searches for blocks by an EM algorithm (Described below), and a similar program MetaMEME (which searches for profiles using HMMs, described below).The Motif Alignment and Search Tool (MAST) for searching through databases for matches to motifs.