Why Is Iron Significant to Understanding How a Supernova Occurs

Multiple Choice

Why is iron significant to understanding how a supernova occurs?

A) Iron is the heaviest of all atomic nuclei, and thus no heavier elements can be made.
B) The fusion of iron into uranium is the reaction that drives a supernova explosion.
C) Iron cannot release energy either by fission or fusion.
D) Supernovae often leave behind neutron stars, which are made mostly of iron.