k-means clustering is a method of vector quantization, originally from signal processing, that is popular for cluster analysis in data mining.
2)Self-Organizing Map Self Organizing Map (SOM) provides a data visualization technique. SOM also represents clustering concept by grouping similar data together.
3)k-nearest neighbors algorithm (k-NN) is a non-parametric method used for classification and regression.
4)Agglomerative hierarchical clustering is a bottom-up clustering method where clusters have sub-clusters, which in turn have sub-clusters, etc.
Hence k nearest neighbour method is not used clustering.
Option C is correct.
