When does a page fault occur?

• A. The requested page is not currently loaded in RAM.
• B. The TLB miss is the same as a page fault.
• C. The page is not currently in RAM, prompting the OS to load it.
• D. The system is in an error state.

Answer: (C)

A page fault happens when a process references a virtual page that is not currently loaded in physical memory. The hardware triggers a trap to the operating system, which then takes action to bring that page into RAM. It locates the page on disk, loads it into a free frame, updates the page table to mark the page as present, and then resumes the faulting instruction. That explains why the option describing the page not being in RAM and prompting the OS to load it is the best choice: it captures both the condition and the OS-driven response. The other ideas don’t fit as cleanly: a TLB miss is about translating addresses cached in the TLB and can occur even if the page is in RAM, and a system error state is not what defines a page fault.