Introduction:
Volatile memory refers to a type of computer memory that requires a continuous power supply to retain data. When the power supply is interrupted or turned off, the data stored in volatile memory is lost. In contrast, non-volatile memory retains data even when the power supply is removed.

Explanation:
Out of the given options, DRAM (Dynamic Random-Access Memory) is the most volatile. Here's why:

1. DRAM (Dynamic Random-Access Memory):
- DRAM is a type of volatile memory commonly used in computers and other digital devices.
- It stores each bit of data in a separate capacitor within an integrated circuit.
- The capacitors in DRAM cells gradually lose their charge over time due to leakage, and therefore, the stored data needs to be refreshed periodically.
- DRAM requires a constant power supply to maintain the stored data. Once the power is removed or interrupted, the data is lost.
- To compensate for this volatility, DRAM modules are typically used in conjunction with non-volatile memory, such as hard drives or solid-state drives, to ensure data persistence.

2. SRAM (Static Random-Access Memory):
- SRAM is another type of volatile memory commonly used in computer systems.
- Unlike DRAM, SRAM uses flip-flops to store each bit of data, which do not require constant refreshing.
- SRAM retains data as long as the power supply is maintained, making it less volatile than DRAM.
- However, SRAM is more expensive and requires more power than DRAM, which limits its usage in certain applications.

3. ROM (Read-Only Memory):
- ROM is a type of non-volatile memory that stores data permanently and does not require a continuous power supply to retain it.
- The data stored in ROM is written during manufacturing and remains fixed throughout the lifespan of the memory chip.
- ROM is commonly used to store firmware, boot loaders, and other essential software that need to be retained even when the power is off.
- Unlike DRAM and SRAM, ROM is not volatile and does not lose its data when the power supply is interrupted or turned off.

4. RAM (Random-Access Memory):
- RAM is a general term that encompasses both volatile and non-volatile memory.
- In this context, it is important to differentiate between volatile RAM (such as DRAM and SRAM) and non-volatile RAM (such as NVRAM or battery-backed RAM).
- DRAM and SRAM are considered volatile RAM because they require a continuous power supply to retain data, while non-volatile RAM retains data even without power.
- Therefore, while RAM can refer to both volatile and non-volatile memory, the term "volatile RAM" is often used to specifically denote DRAM and SRAM.