In the smectic A liquid-crystalline phase, . a. the molecules are oriented in a totally random fashion b. disk-shaped molecules are aligned through a stacking of the disks in layers c. the molecules are aligned along their long axes, with no ordering with respect to the ends of the molecules d. the molecules are aligned with their long axes tilted with respect to a line perpendicular to the plane in which the molecules are stacked e. the molecules are arranged in sheets, with their long axes parallel and their ends aligned as well