What organization is responsible for developing network media specifications?

The Institute of Electrical and Electronics Engineers, commonly known as IEEE, plays a crucial role in the development of network media specifications. This organization is renowned for creating standards that govern various aspects of electrical and electronic technologies, including those related to networking.

The IEEE's standards, such as the Ethernet protocols (IEEE 802.3) and wireless standards (IEEE 802.11), define how data is physically transmitted over various media types. These standards are essential for ensuring interoperability between devices and creating a reliable framework for communication within networks. The specifications cover aspects such as signal encoding, physical connections, and data transmission methods.

The other organizations mentioned, such as ISO (International Organization for Standardization) and IEC (International Electrotechnical Commission), focus on broader standardization efforts across various industries but do not primarily specialize in the specifics of network media. W3C (World Wide Web Consortium), on the other hand, is dedicated to web standards and technologies and does not engage in the development of network media specifications. Hence, IEEE's focused contributions make it the correct answer for this question.