What does an indexing operation accomplish in file or database systems, with respect to how data is accessed and organized?

Introduction / Context:
Indexes accelerate data retrieval by maintaining auxiliary structures that allow rapid lookup without scanning an entire file or table. Understanding what “indexing” means distinguishes it from physically sorting data, which changes the order of records themselves rather than providing a separate access path.

Given Data / Assumptions:

• We are discussing indexing in the sense of creating access paths (e.g., B-tree, hash).
• Sorting a file reorganizes the data physically; indexing builds a separate structure.
• The goal is faster search, join, and filter operations.

Concept / Approach:
An indexing operation establishes an index—a data structure that maps key values to record locations. While data might be scanned or sorted for index creation, the essence of indexing is the creation and maintenance of the index structure, not the permanent sorting of the base file by one or multiple keys.

Step-by-Step Solution:

Verification / Alternative check:
DBMS manuals describe CREATE INDEX as creating a separate structure; the table’s physical order typically remains unchanged.

Why Other Options Are Wrong:

• Sorts by single/two keys: Sorting is different from indexing; an index does not require the table to be sorted.
• Both (b) and (c): Includes an incorrect element (sorting) alongside the correct one.
• None: Incorrect because indexing indeed establishes an index.

Common Pitfalls:
Thinking that an index always implies a physically sorted table; assuming multi-key sorts equal multi-column indexes.

Final Answer:
Establishes an index for a file