(A) Discuss the connections and differences between partitional clustering and hierarchical clustering. (B) Explain self-organizing map and its "topology preserving properties". (C) Training self-organizing map needs to specify several parameters. Name three parameters and explain their purpose. (D) Given a set of points, students A and B apply k-means clustering to cluster these points into M clusters, respectively. Due to various reasons, their clustering results are not identical. You are invited to determine whose clustering result is better. Please describe your solution.