During the day Kim, an administrator, noticed the network slowing down. Within an hour, the network was showing 100% utilization. While investigating the issue, Kim notices that most of the traffic is coming from one switch. Which of the following scenarios is MOST likely the cause?

A.
The switch was configured for QoS and was bottlenecking all traffic.

B.
Kim has implemented VLAN trunking on the switch.

C.
A user has moved a laptop from one wall jack to another triggering port security.

D.
A user plugged both ends of a patch cable into the switch jacks.