Users in the Network Discovered That the Efficiency of a File

Users in the network discovered that the efficiency of a file transfer is low. The administrator used wireshark to observe the network and discovered many duplicate frames. Which statement correctly explains the reason for this?

A) The switch doesn't know the destination and has flooded frames.
B) This network needs upgrading to use newer and more efficient switches.
C) The network has loops at the link layer.
D) The network has not been segmented using VLANs.