Which statement best defines a distributed database in terms of logical unity and physical distribution across networked locations?

Introduction / Context:
Distributed databases present a unified logical view of data even when the data is physically partitioned or replicated across multiple sites. This definition distinguishes them from simple file sharing or isolated databases.

Given Data / Assumptions:

• Multiple sites connected via a network.
• Transparency goals (location, fragmentation, replication) typical in distributed DBMS.
• Unified schema or global catalog provides the single logical view.

Concept / Approach:
A distributed database is one logical database that spans sites. Users query it as if it were centralized; the DBMS handles routing, fragmentation, and replication behind the scenes.

Step-by-Step Solution:

Verification / Alternative check:
Classic distributed DB definitions (for example, Ceri & Pelagatti) emphasize logical integration with physical distribution.

Why Other Options Are Wrong:

• B and D: describe loose file collections, not DBMS-managed databases.
• C: describes a centralized database.

Common Pitfalls:
Equating “federated” file access or ETL copies with a distributed DBMS; the latter supplies a global schema and query processing.

Final Answer:
A single logical database that is spread to multiple locations and is interconnected by a network