The paragraph below describes a clustering algorithm:

"First, the distance between two clusters is measured as the distance between the average attributes of the two clusters.

Second, follow the following three steps.

Step 1: Start by considering that all observations belong to their own unique cluster.

Step 2: Merge the two clusters that have the smallest distance to each other, to create one single cluster.

Step 3: Repeat step 2 multiple times until all observations belong to the same one cluster."

What is the name of the clustering algorithm described above?

a.

Ward's method

b.

Complete linkage

c.

Average linkage

d.

k-means clustering

e.

Centroid method