For what phrase does the term 'Quasar' stand?

• A. Quasi-stellar radio signal
• B. Quasi-stellar radiation source
• C. Quasi-solar radio source
• D. Quasi-stellar radio source(s)

Answer: (D)

Quasi-stellar radio source(s) is the phrase that fits because a quasar was named for being a star-like (quasi-stellar) object that was identified as a source of radio waves. The term captures two key ideas: the optical appearance in telescopes looks like a point-like star, and the object is detected as a radio source. The “star-like” part explains the name, while “radio source” reflects how these objects were first discovered and studied in radio surveys. The plural form acknowledges that many such objects are not strong radio emitters, yet the original label comes from their nature as radio sources. The other options miss one of these pieces: they either replace “source” with something like “signal” or “radiation” or swap “stellar” for “solar,” which changes the meaning away from the star-like appearance and the radio-emitting nature.