Cluster Shapes for $k-$Means versus Single Linkage

Heidi Zahn is a human resources manager currently reviewing data on $98$ employees. In the data, each observation consists of an employee's age and an employee's performance rating.

a$.$ Heidi applied $k-$means clustering with $k=2$ to the data and generated the following plot to visualize the clusters. Based on this plot, qualitatively characterize the two clusters of employees categorized by the k$-$means approach.

$k-$Means Clustering Solution with $k=2$