The following statements are true:
* Networks are segmented into multiple collision domains using switches for CSMA/CD networks
* CSMA/CD networks normally operate on half-duplex mode
* Gigabit Ethernet uses CSMA/CD as its media access control method

CSMA/CD is a Local Area Network (LAN) access method used in Ethernet. In CSMA/CD, if a device or a node wants to send a packet in the network, it first determines if the network is free. If the network is not free, then the node will wait before sending the packet into a network. If the network is free, then the node sends the packet; if another device sends a packet simultaneously, their signals or packets collide. When the collision is detected, both packets wait for a random amount of time before retrying.

The option stating that networks are segmented into multiple broadcast domains using switches for CSMA/CD networks is incorrect because networks are segmented into multiple broadcast domains using routers for CSMA/CD networks.

The option stating that CSMA/CD networks normally operate on full-duplex mode is incorrect; these networks normally operate on half-duplex mode. The option stating that gigabit Ethernet uses CSMA/CA as the media access control method is incorrect because gigabit Ethernet uses CSMA/CD as the media access control method.