Read the passage below and answer the question that follows:
Astronomers long believed that interstellar dust grains formed primarily in the expanding envelopes of cool giant stars. However, recent observations of distant submillimeter galaxies revealed massive dust reservoirs produced when the universe was less than a billion years old. Since giant stars require several billion years to evolve and shed dust, some astrophysicists hypothesized that core-collapse supernovae—the explosive deaths of massive stars—must be the dominant source of early dust. Conversely, a third group of researchers argues that while supernovae produce initial seed grains, most dust growth actually occurs through the accretion of gas-phase atoms in the cold interstellar medium itself, rather than inside stellar ejecta.
Match each theoretical perspective on interstellar dust formation to the core argument or evidence that supports it.
- Cool Giant Star HypothesisTraditional astronomical models hold that dust forms gradually over long timescales within the expanding outer atmospheres of aging stars.
- Core-Collapse Supernova HypothesisSubmillimeter observations of early galaxies require rapid dust production from massive, short-lived stellar explosions because lower-mass stars evolve too slowly.
- Interstellar Medium Accretion HypothesisDust accumulation occurs mainly as gas-phase atoms condense onto existing seed grains in cold space rather than inside stellar ejecta alone.