Which type of memory retains data without a power supply?

The correct choice is non-volatile memory because this type of memory is specifically designed to retain data even when the power supply is removed. Non-volatile memory stores information in a way that allows it to remain intact across power cycles, making it essential for applications where data persistence is critical, such as in storage devices and firmware.

Flash memory and EEPROM (Electrically Erasable Programmable Read-Only Memory) are specific types of non-volatile memory. While both do retain data without a power supply, they fall under the broader category of non-volatile memory. Thus, selecting non-volatile memory encompasses all types that maintain data permanence, while the other choices focus on specific implementations or types that also fall within that category.

In contrast, RAM (Random Access Memory) is a volatile memory type, meaning it requires a continuous power supply to retain data. Once the power is turned off, all data stored in RAM is lost. Therefore, it cannot be considered in this context of retaining data without power.