Nhich of the following statements is correct? * a. In most cases positions, directions and planes of cubic crystal structures are indexed in terms of conventional rather than primitive lattice vectors. b. In most cases, positions and directions are indexed in terms of primitive rather than conventional lattice vectors, while planes are indexed in terms of conventional lattice vectors. c. In most cases positions, directions and planes of crystals are indexed in terms of primitive rather than conventional lattice vectors. d. In most cases positions, directions and planes of crystals are neither indexed in terms of conventional nor indexed in terms of primitive lattice vectors e. In most cases, planes and directions are indexed in terms of primitive rather than conventional lattice vectors, while positions are indexed in terms of conventional lattice vectors.