What is the difference between a GBIC and an SFP?

The option that states SFP is used for Gigabit interfaces and is smaller than GBIC is correct due to several important aspects of these two types of interfaces.

The SFP, or Small Form-factor Pluggable, is designed to provide a more compact and efficient option for connecting network devices compared to the GBIC, or Gigabit Interface Converter. One of the primary distinctions is the physical size: the SFP is indeed smaller, allowing for higher density configurations within networking equipment. This smaller form factor enables more SFP ports to fit into the same space as a GBIC, which is advantageous for creating more compact network designs and conserving rack space.

Additionally, both GBIC and SFP can support Gigabit interfaces, but the SFP has become the more prevalent choice in modern networks, largely due to its size and versatility in supporting various types of connections, such as fiber optic and copper cabling. Understanding these characteristics helps network professionals choose the appropriate transceiver for their specific networking requirements.