Why should disk and network I/O be used to identify bottlenecks?

A.
High disk and network I/O utilization of the Delivery Controller can indicate a high volume of user logons, indicating that the server may NOT have sufficient
resources to handle the load.

B.
High disk and network I/O utilization on the Delivery Controller can indicate that the target device will encounter delays when mounting new vDisks.

C.
High disk and network I/O utilization of the Delivery Controller may indicate that a high number of processor-intensive applications are being utilized by the
virtual desktop users.

D.
High disk and network I/O utilization of the Delivery Controller can indicate the presence of a virus or malware.