no two sides are EQUAL i.e. `a!=b!=C` all CRYSTALLOGRAPHIC angles are equal to `90^(@)` i.e. `alpha=beta=gamma=90^(@)` three kinds of unit cells are found, these are primitive, body centred and face centred all FOUR unit cells are found.
Solution :All the four unit cells are found i.e. primitive, body centred, face centred and END centred.