What is true about white dwarfs compared to the Sun?

White dwarfs are indeed generally hotter than main-sequence stars like the Sun, despite their faintness. After a star like the Sun has exhausted its nuclear fuel, it expands into a red giant and ultimately sheds its outer layers, leaving behind a dense core that becomes a white dwarf. These remnants are comprised mainly of electron-degenerate matter and can reach extremely high temperatures, often exceeding those of the Sun during their initial stages.

The reason a white dwarf can be hotter yet fainter lies in its relatively small size and the fact that it no longer undergoes nuclear fusion, which is what powers stars like the Sun and produces light. In a white dwarf, although the surface temperature can be quite high—often above 100,000 K—the star has a much lower luminosity because its small size and low surface area lead to less overall light output.

In contrast, while other choices suggest various comparisons regarding brightness and temperature, they do not accurately capture the relationship between white dwarfs and the Sun in terms of thermal states and luminosity. Thus, the true statement regarding white dwarfs is that they are generally hotter than the Sun while also being faint due to their size and lack of ongoing fusion reactions.