What is the most likely cause of these problems?

Refer the Exhibit. A Cisco 10/100/1000 Mbps switch is inserted in a small office network. The two servers and three user workstations are configured as shown in the diagram. After inserting the switch, server to server communication is fine, but performance and communication to/from user workstations is poor. What is the most likely cause of these problems?

A.
Connections to user workstations improperly configured as Trunk ports

B.
Auto negotiation failure causing duplex mismatches only on 100Mpbs interfaces

C.
Bad or faulty Ethernet NICs on the user PCs

D.
Bad or faulty Ethernet ports/controllers on the Cisco 10/100/1000 switch

E.
Failure to configure user workstation interfaces for spanning tree portfast

Explanation:
A is incorrect because very rarely will mulitple NIC’s fall on multiple PC’s at the same time. The common denonator in this instance is the installation of the switch B is incorrect because no sign of wrong configuration is shown C is incorrect because it is also an extreamly rare occurance D is incorrect because user workstation ports do not participate in Spanning tree E is correct and can be a common occurance this reequires the port speed to be statically configured on the 100mbps switch ports