Question

the largest stars will continue to fuse elements until it fuses iron. when a stars core is primarily composed of iron, it can no longer produce energy through fusion. the core becomes collapses, becoming an increasingly dense center. when that system collapses, all of the material ejects out in a catastrophic event called a supernova, where the star collapses under its own gravity and explodes, releasing a tremendous amount of energy and scattering the newly formed elements into space. the largest of these become black holes, while the smaller become neutron stars.
describe a supernova
which arrow causes the star to collapse on itself?
gravity
fusion

Explanation:

Step1: Understand star - core dynamics

When a star's core is mainly iron, fusion stops. Gravity is the force that pulls matter inwards.

Step2: Identify the collapsing force

The outward - pushing force from fusion is no longer there. Gravity, which always acts inwards, causes the star to collapse on itself.

Answer:

Gravity