To solve this question, we need to identify which types of memory/storage are volatile. Volatile memory is a type of computer memory that requires power to maintain the stored information; it loses its content when the computer is turned off.

Let's analyze each of the options:

1. RAM (Random Access Memory): RAM is a volatile memory, meaning it loses its data when the power is turned off. It is used by computers to store data that is being currently processed.
2. ROM (Read-Only Memory): ROM is non-volatile, meaning it retains its data even when the power is turned off. It is used to store firmware.
3. Cache: Cache memory is also a type of volatile memory. It is a small-sized type of volatile computer memory that provides high-speed data access to a processor and stores frequently used computer programs, applications, and data.
4. SSD (Solid State Drive): SSD is non-volatile storage that retains data even when the power is turned off. It uses flash memory to provide faster data access than a traditional HDD.
5. HDD (Hard Disk Drive): HDD is another non-volatile storage, storing data permanently until manually deleted, powered off, or overwritten.

From the analysis above, we see that both RAM and Cache are volatile memory types while ROM, SSD, and HDD are non-volatile.

Thus, the correct answer is: A and C Only.