In the Spark UI's Storage tab with MEMORY_ONLY storage level, the indicators of a non-optimally cached table are:

• B: The '*' annotation in the RDD Block Name indicates partitions that couldn't be cached due to memory constraints, leading to recomputation.
• C: Size on Disk > 0 is unexpected for MEMORY_ONLY, as it implies data spillage to disk (which is not allowed in MEMORY_ONLY). This suggests a misconfiguration or unintended storage level usage, impacting performance.

Options A (normal for MEMORY_ONLY), D (impossible partition count), and E (irrelevant for MEMORY_ONLY) are incorrect.