In Order for an Atom to Substitute for Dominant Atoms

Multiple Choice

In order for an atom to substitute for dominant atoms in a crystal structure, and therefore alter its color, what must occur?

A) The atom must be similar in size to the crystal's atoms.
B) The atom must have the same charge as the crystal's atoms.
C) The atom must be close in electronegativity values to the crystal's atoms.
D) The atoms must be close to each other on the periodic table of elements.