Final answer:
The malware that resides only in RAM is known as a Memory-resident virus, distinguishing it by its ability to stay in memory and infect other programs while the system is running.
Correct option is d) Memory-resident virus
Step-by-step explanation:
A memory-resident virus is a type of malware specifically engineered to operate exclusively within a computer's volatile memory (RAM). Unlike traditional viruses, worms, Trojans, or rootkits, a memory-resident virus does not rely on a presence in storage media files. Instead, it stays in the computer's memory even after execution, discreetly infecting other programs as they run or are opened. This characteristic makes it particularly elusive, as it can persist without leaving traces in the file system.
However, the volatility of its presence becomes evident upon system reboot; when RAM is cleared, the memory-resident virus is eradicated. This unique modus operandi emphasizes the importance of real-time security measures to detect and prevent the injection of such viruses into the system's memory.