Which factor makes dynamic RAM (DRAM) volatile?

Dynamic RAM (DRAM) is considered volatile because it relies on electrical charges to store bits. In DRAM, each bit of data is stored in a tiny capacitor that holds an electrical charge. When the power is turned off or interrupted, the electrical charge dissipates quickly, causing the stored data to be lost. This reliance on electrical charges as a means of storage is what makes DRAM volatile, meaning that it cannot retain data once power is removed.

Other factors mentioned in the options do not align with the characteristics of volatile memory. For instance, the notion of storing data permanently contradicts the definition of volatility; volatility inherently refers to the inability to retain data without a power supply. Similarly, while DRAM does indeed have a more complex architecture compared to static RAM (SRAM), this complexity does not directly relate to its volatile nature. Lastly, the ability to retain data without power is a characteristic of non-volatile memory types, such as flash memory, further distinguishing DRAM as a volatile memory.