Twinaxial (Direct Attach Copper / DAC) cables can plug directly into QSFP ports without needing separate optical transceivers. They are cost-effective for short-distance, high-speed connections (commonly in data centers).
A). Multimode fiber requires SFP/QSFP transceivers to convert electrical signals to optical.
C). RG11 is coaxial cable for broadband/cable TV, not used in QSFP ports.
D). Category 6 is twisted-pair Ethernet cabling, not directly compatible with QSFP ports.
References (CompTIA Network+ N10-009):
Domain: Network Infrastructure - Cable types, QSFP, DAC (Twinaxial), transceiver requirements.