Difficulty: Easy
Correct Answer: Key
Explanation:
Introduction / Context:
Every well-designed file or table needs a way to uniquely identify each record. This unique identifier supports retrieval, updates, and relationships across files or tables, and prevents ambiguity or duplicates in transactional operations.
Given Data / Assumptions:
Concept / Approach:
A key is an attribute or set of attributes that uniquely identifies a record. In relational systems this is the primary key; in files it may be a record key used by indexing and access methods. Keys also enable foreign key relationships and enforce entity integrity.
Step-by-Step Solution:
1) Identify the requirement: uniqueness across all records.2) Map to standard data management terminology: "key".3) Recognize variants: natural keys, surrogate keys, composite keys.4) Confirm that none of the other options describe uniqueness.
Verification / Alternative check:
Database design texts and file organization references consistently use "key" to denote the unique identifier that supports indexing and access paths.
Why Other Options Are Wrong:
Response time: a performance metric, not an identifier.System review: a governance activity, not a data attribute.Test data: sample records for validation, not an identifier.None of the above: incorrect because "Key" is correct.
Common Pitfalls:
Using non-unique attributes as identifiers or allowing nullable keys leads to integrity problems and difficult joins.
Final Answer:
Key
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