Which technology helps in detecting when two devices are trying to communicate at the same time?

CSMA/CD, which stands for Carrier Sense Multiple Access with Collision Detection, is a network protocol that helps manage how devices on a shared communication medium can transmit data without interfering with each other. When multiple devices attempt to send data simultaneously, collisions can occur. CSMA/CD helps mitigate this issue by allowing devices to "listen" to the network traffic before they transmit. If a device detects that the medium is already in use, it will wait until it is free before sending its data. Additionally, if a collision is detected during transmission, CSMA/CD provides a mechanism for the devices to stop transmitting, back off for a random amount of time, and then attempt to resend their data. This collision detection capability is fundamental to ensure efficient communication in networks that utilize shared mediums, particularly Ethernet networks.

In contrast, the other options like Token Ring manage access to the network differently, using a token-passing method rather than relying on collision detection. Simplex communication involves one-way communication paths, thereby not requiring collision detection, while a Local Area Network (LAN) is a broader term that describes a network of devices in a limited area and does not specify any method for handling simultaneous transmissions.