What is the purpose of an SFP (Small Form-factor Pluggable) transceiver, and what flexibility advantage does it provide over a fixed-media switch port?

• A.An SFP is a USB-to-Ethernet adapter that provides additional ports on switches that have run out of built-in ports; additionally, a Layer 2 switch rewrites source MACs to its own address on egress, as routers do. An edge router marks QoS by rewriting destination IP addresses into the EF range
• B.An SFP is a hot-swappable modular transceiver that fits into a standard cage on a switch or router; by swapping SFP modules, the same physical port can support different media types (copper 1000BASE-T, multimode fiber 1000BASE-SX, single-mode fiber 1000BASE-LX) without replacing the switch
• C.An SFP is a software module installed on the switch OS to enable QoS or VLAN tagging features; a transparent firewall requires readdressing both adjacent subnets. An IPS must be deployed on a SPAN port to block traffic inline. Smart jacks are customer-owned devices that terminate the LAN side of a demarc
• D.An SFP increases port speed from 1 GbE to 10 GbE by adding a signal booster to the existing copper port