_________ is issued if a desired page is not in main memory.Select one:A.page replacement policyB.page placement policyC.paging errorD.page fault

Break Down the Problem

1. Identify the key terms and concepts in the question.
2. Focus on the definitions of the options provided.

Relevant Concepts

1. Page Fault: This occurs when a program tries to access a page that is not currently mapped to the main memory.
2. Page Replacement Policy: This defines how a system decides which page to remove when new pages are loaded into memory.
3. Page Placement Policy: This determines where in the memory a new page is loaded.
4. Paging Error: This refers to an issue that might occur in the paging system, but it's not the commonly used term for the event described in the question.

Analysis and Detail

1. A Page Fault directly corresponds to the situation described: when a desired page is not in main memory, a page fault is triggered to retrieve the page from secondary storage.
2. The other options describe policies or concepts that do not specifically refer to the absence of a page in memory.

Verify and Summarize

• After analyzing the definitions of each option, it's clear that the occurrence when a desired page is not in main memory is best described by the term "page fault."

Final Answer

D. page fault