Which of the following are radio frequency connections?

CompTIA A+ explains that radio frequency (RF) connections use electromagnetic waves instead of copper or optical cabling. Satellite uses RF signals transmitted to and from orbiting satellites, while cellular networks (3G/4G/5G) use RF communications via cell towers.

Cable uses coaxial wired infrastructure, DSL uses telephone lines, Ethernet is twisted-pair copper, and fiber uses light instead of RF.

Satellite and cellular are the only technologies in the list that rely on wireless radio frequency transmission as their medium. The A+ networking domain emphasizes understanding the physical media of WAN technologies and distinguishing wired vs. wireless connectivity, making B and D the correct answers.