the death of a low-mass star the gravity of a large nebula the collapse of a high-mass star the combining of material from planets
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Astronomers have found evidence for the existence of a super-massive black hole in the center of the giant elliptical galaxy M87. What is thought to cause black holes to form?
Possibilities:
- the death of a low-mass star
- the gravity of a large nebula
- the collapse of a high-mass star
- the combining of material from planets

the collapse of a high-mass star