Identify situations in which clustering occurs.

Clustering occurs in situations where individuals gather or form groups based on shared characteristics, experiences, or behaviors. In the context of the options provided, when athletes register in classes involving little work, it indicates that they are likely clustering together based on their desire for a less rigorous academic load. This behavior reflects a shared interest in managing their schedules to accommodate the demands of their athletic commitments.

The other scenarios do not illustrate clustering in the same way. Practicing independently does not involve grouping with others, seeking mentors indicates a one-on-one relationship rather than a collective gathering, and working in peer study groups, while collaborative, does not inherently relate to the specific shared characteristic of seeking low-work classes that would define clustering. Therefore, the correct answer highlights a key aspect of clustering based on common preferences among athletes.