Fact 1: Ablack hole is formed by a high-mass star collapses.

Fact 2: Black holes are considered to be spheres.

Given the two facts above, answer the question "what does a high-mass star collapsing form?" with the following options: 
- forces
 - a sphere
 - a cube
 - a circle
 - dangerous
 - an object
 - comets
 - nucleus


 

  a sphere       