Which statement best describes an interstitial alloy?
a) Atoms of comparable size replace one another at regular lattice points.
b) Smaller atoms occupy the spaces between the host metal atoms in the lattice.
c) Vacancies created by missing host atoms serve as the primary strengthening feature of an interstitial alloy.
d) Oversized impurity atoms crowd into the lattice holes, stretching the crystal structure and forming an interstitial alloy.