15 A customer is using file pool policies to archive infrequently accessed files to Amazon S3 viaCloudPools. How could the customer easily find out how many stub files are stored on the cluster?
选项：

A: OneFS WebUI can be used to show how many stubs are stored in each node pool
B: InsightIQ can report the number of stub files stored on the cluster
C: The isi statistics CLI command can be used to show how many stubs are stored in each node pool
D: The number of stub files stored on a cluster is not easily available