The smallest stars are called

• A. White dwarfs
• B. Protostars
• C. Brown dwarfs
• D. Red giants

Answer: (B)

In star formation, the smallest objects that are actively in the process of becoming a star are protostars. They form when a dense clump in a molecular cloud collapses under gravity, creating a compact, growing core that glows mainly from the heat of accreting material rather than sustained hydrogen fusion. Protostars are the smallest stage in a star’s life before fusion starts, so they’re described as the smallest stars in the context of stellar birth. If enough mass accumulates and core temperatures rise, fusion begins and the object becomes a true, main-sequence star (often a red dwarf at the low-mass end). If fusion never starts, the object ends up as a brown dwarf, which is not considered a true star. The other options describe stages or categories that aren’t the smallest forming stars: white dwarfs are compact remnants after a star’s life, red giants are large evolved stars, and brown dwarfs are substellar bodies that don’t sustain fusion.