Answer: Clustering
Explanation:
Clustering is the technique through which elements of items are gathered in a group or collection.This is usually done to make the groups of the items that persist the same trait or quality so that it can be easily managed and organized for certain purpose.
According to the question, Maria is using the method of clustering to group the adjacent states of the United states so that she can recall them through naming it by clustering the states separately New England, Mid-Atlantic states ,Southeast state etc.