Final answer:
Heavy elements past iron are synthesized primarily during supernova nucleosynthesis when massive stars explode at the end of their lives, scattering these new elements into the cosmos. The correct option is a).
Step-by-step explanation:
Heavy elements past iron are made primarily through a process known as supernova nucleosynthesis, which occurs during the explosive end-of-life events of massive stars.
In the universe, nuclear fusion within stars creates elements up to iron, but heavier elements are synthesized during the tremendous energy release of a supernova explosion. This explosion generates shock waves and high temperatures that enable the combination of existing atomic nuclei to form new, heavier nuclei.
When a massive star has converted its core to an iron-nickel mix, it no longer gains energy from fusion because reactions involving iron absorb energy instead of releasing it.
The star ultimately collapses under its own gravity, which leads to a supernova. It is during this cataclysmic explosion that conditions are favorable for the production of elements heavier than iron.
The resulting elements are then scattered into interstellar space, contributing to the cosmic enrichment that leads to subsequent generations of stars and planetary systems with these heavy elements. Option a) is the correct one.