Answer:
The correct answer is: b. intermediate- to low-mass stars (between 0.8x to 8x the mass of our Sun).
Explanation:
Once the hydrogen in the nucleus is finished, the hydrostatic equilibrium is broken, and gravity is able to overcome radiation. This causes the star's core to contract, thus increasing its internal temperature and density. Meanwhile, due to convection, the outer layers expand, so the external temperature decreases. The star increases its external size becoming what we know as the Red Giant.
By increasing the temperature in the core, the necessary conditions are given to begin to fuse Helium and convert it into Carbon. So the core is getting denser and the outer layers of the star expand even more.
The end of our star is marked by the moment when the helium in the nucleus ends. In addition, the outer layers are so far apart that they no longer exert sufficient pressure to compress the core and trigger carbon fusion. In parallel, the star is so large that the outer layers of the star escape the gravity of the star, pushed by radiation. In this way, the interstellar medium of helium, carbon and a little oxygen is enriched. Leaving behind a White Dwarf, the nucleus of the star in which Helium has become Carbon.
