Why Is the Nucleosynthesis Era So Important in Determining the Chemical

Multiple Choice

Why is the nucleosynthesis era so important in determining the chemical composition of the universe?

A) All the elements except hydrogen were produced in the nucleosynthesis era.
B) We can observe spectra from this era to determine what the primordial mix of the elements was at the beginning of the universe.
C) Except for a small amount of elements heavier than helium produced later by stars, the chemical composition of the universe is the same now as at the end of the nucleosynthesis era.
D) We can study the processes that occurred during the nucleosynthesis era to determine how most of the elements in the universe were created.
E) By knowing how much matter was created during the nucleosynthesis era, we can determine whether the universe is open or closed.