In a cross-point memory with resistive elements placed at the intersections of row and column lines, which element is placed in series with the storage element to prevent current from sneaking through unselected cells?

Answer: C. Selector

Cross-point memory can be very dense because there is no transistor at each intersection, but sneak currents through unselected cells interfere with reading. A selector element, which passes almost no current below a certain voltage, is placed in series with the storage element to suppress sneak currents.