For which category of Ethernet is the standard 802.3an utilized?

The standard 802.3an is specifically utilized for 10GBASE-T Ethernet, which supports a data rate of 10 Gbps over twisted-pair cabling. This standard was developed to facilitate high-speed networking over copper cabling, allowing for effective networking solutions in data centers and enterprise environments.

10GBASE-T operates over Cat 6a or higher cabling and can achieve distances up to 100 meters. The use of twisted-pair cabling for such high speeds represents a significant advancement, allowing more flexibility in wiring infrastructure without requiring fiber optics for shorter distance communications.

While the other option categories provide various speeds and capabilities, they do not correspond to the 802.3an standard. 10BASE-T, 100BASE-T, and 1000BASE-T have their respective standards — 802.3, 802.3u, and 802.3ab — each catering to their specific network speeds and technologies.