Which two atoms form an ionic bond? A. Sodium and bromine
B. Two oxygen atoms
C. Two sodium atoms
D. Fluorine and chlorine

A, sodium and bromine. You can think of ionic bonds as happening between elements from different sides of the periodic table. Think of something like table salt, NaCl, which would dissociate into a Na+ ion and a Cl- ion.

It is evolution, because we all have some of the same traits like eye color or shape or ears.