When optimizing the number of clusters for a dataset, the G2M platform will pick the number of clusters associated with the highest Silhouette score. Note that the Silhouette score is most relevant when dealing with well-behaved, i.e. convex-shaped, clusters. In many real-life cases clusters are not convex and the Silhouette score may no longer be relevant. In this case you are best served relying on your domain expertise to identify the most relevant number of clusters.