A clustering technique that permits a convenient graphical display is :

Concept: Cluster-analysis methods are usually grouped into three broad families. Partition-based methods (e.g. k-means) fix the number of clusters in advance and output one flat, non-overlapping grouping. Probabilistic model-based methods fit a mixture of probability distributions to the data and report a membership probability for each point rather than a rigid grouping. Hierarchical methods instead build a nested, multi-level structure by successively merging or splitting groups; that nested structure is exactly what can be drawn as a dendrogram, so hierarchical clustering is the family credited with permitting a convenient graphical display of the clustering result.

Application: Checking each family against the property asked for in the question -

• Partition-based clustering commits to a fixed cluster count k up front and returns a single-level partition, so there is no natural multi-level diagram to draw from it.

• Probabilistic model-based clustering outputs soft membership probabilities from a fitted mixture model; the result is a set of probabilities, not a tree.

• Hierarchical clustering builds the nested sequence of groupings level by level, and this nested sequence is the structure that is conventionally displayed as a dendrogram.

• Agglomerative clustering is a specific bottom-up procedure inside the hierarchical family - it starts with every point as its own cluster and repeatedly merges the closest pair until one cluster remains. Because it is one particular algorithm within hierarchical clustering rather than a separate top-level family alongside partition-based and probabilistic model-based clustering, the classification-level option that matches the question is hierarchical clustering itself.

Cross-check: This matches how the question is set up as a choice between clustering FAMILIES (partition-based, probabilistic model-based, hierarchical) with one specific hierarchical algorithm (agglomerative) added as a close-sounding distractor; it also matches the answer recorded in independently available solved copies of this UGC NET June 2009 Paper II (Computer Science) question. So the family that permits the convenient graphical display is hierarchical clustering.