At the end of its evolution, a star can become the following:
- A neutron star - This is one of the possible outcomes after a supernova for massive stars.
- A black hole - This is another possible outcome after a supernova, specifically for very massive stars.
- A white dwarf - This is the final stage for average stars after they evolve from a planetary nebula.
The correct responses are:
- a neutron star
- a black hole
- a white dwarf
Therefore, the responses a neutron star, a black hole, and a white dwarf are the three correct answers.