Why Is an Iron Atom a Different Element Than a Carbon

Multiple Choice

Why is an iron atom a different element than a carbon atom?

A) A carbon atom has fewer neutrons in its nucleus than an iron atom.
B) An iron atom has more protons in its nucleus than a carbon atom.
C) An iron atom has more electrons than a carbon atom.
D) A carbon atom is bigger than an iron atom.
E) All of the above are true.