Which of the following protocols operates at speeds of 1000 Mbps?

The protocol that operates at speeds of 1000 Mbps is primarily defined as 1000BaseT. This standard is part of the Ethernet family and supports Gigabit Ethernet over twisted-pair cabling, specifically designed for use with high-speed data transmission.

1000BaseT achieves this speed through the use of all four pairs of wires in a Category 5 (or better) cable, allowing simultaneous transmission and reception of signals. This makes it a suitable choice for modern networks that require faster data transfer rates to support bandwidth-intensive applications.

In contrast, the other protocols listed operate at lower speeds. For instance, 100BaseT refers to Fast Ethernet with a maximum speed of 100 Mbps, while 10BaseT operates at only 10 Mbps. The term "Ethernet" is more general and does not specify a particular speed, as it encompasses various standards, including those with speeds lower than 1000 Mbps. Thus, 1000BaseT is the correct answer as it definitively specifies the protocol that directly operates at the 1000 Mbps speed.