human
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?

Choices:
A) the death of a low-mass star
B) the gravity of a large nebula
C) the collapse of a high-mass star
D) the combining of material from planets
gpt
The correct answer is 2: the collapse of a high-mass star.