According to the IEEE 802.3 standard, what is defined?

The IEEE 802.3 standard specifically defines the physical layer and data link layer's specifications for Ethernet. This standard encompasses various aspects of Ethernet networking, including the transmission methods, signaling, and the structure of frames in Ethernet communications. It has evolved since its inception in the 1980s to support different speeds and media, from the earliest 10 Mbps Ethernet to modern fiber-optic implementations at 100 Gbps and beyond.

In contrast, fiber optics, while relevant in transmitting Ethernet signals, is just one of the media types that can be used within the Ethernet framework defined by IEEE 802.3. Wi-Fi is governed by the IEEE 802.11 standards, which focus on wireless communication, and Token Ring is a network protocol defined by IBM, not IEEE. Therefore, the correct choice reflects the foundational technology for wired computer networking that IEEE 802.3 outlines.