Which OSI layer is described as providing a path for the transmission of bits over cables, fiber, and radio waves?

• A. Physical Layer (Layer 1)
• B. Data Link Layer (Layer 2)
• C. Network Layer (Layer 3)
• D. Application Layer (Layer 7)

Answer: (A)

The key idea here is the actual transmission of raw bits over the physical medium. The Physical Layer defines how signals are represented and transmitted over cables, fiber, and wireless (including voltage levels, timing, synchronization, and the hardware interfaces like NICs and connectors). It’s the bottom layer that carries the bits themselves from one device to another, without concerns about how those bits are formatted into frames, routed across networks, or consumed by applications. The data link layer handles frames and error detection, the network layer handles routing and addressing, and the application layer deals with software interfaces; none of these manage the raw bit transmission over the physical medium like the Physical Layer does.