All changes in phase are
a) chemical changes.
b) physical changes.
c) chemical reactions.
d) chemical properties.

All changes in phases are physical changes. Physical changes are those that does not change the chemical bonds: the atoms in the molecules continue being bonded to the same atoms and, consequently, the composition of the compound does not change. Changes in phase leads to changes in the separation of the molecules (generally speaking molecules in solids are very close, molecules in liquids are more separated and molecules in gases are fr from each other), but do not change each molecule per se. So the answer is the option B) physical changes.