What type of star is described as a degenerate star or an aged star?

A white dwarf is accurately described as a degenerate star or an aged star because it represents a late stage in the life cycle of a star like our Sun. After exhausting its nuclear fuel, a star will shed its outer layers, often leading to the formation of a planetary nebula while the core remains. This remaining core, now a white dwarf, is incredibly dense, consisting primarily of electron-degenerate matter, meaning that the electrons are packed closely together.

As a white dwarf cools over time, it no longer undergoes fusion reactions; instead, it simply radiates its residual heat into space. The process of becoming a white dwarf is a critical phase in stellar evolution, marking the end of the star's life cycle, which is a significant aspect of its classification as an aged star. In contrast, neutron stars are the remnants of supernova explosions and do not represent the same evolutionary stage as white dwarfs. The other choices (red supergiants and red giants) refer to stages where fusion is still ongoing and the stars are not considered degenerate. Hence, the distinguishing characteristics of a white dwarf firmly establish it as a degenerate star and a reflection of stellar aging.