Who places “explicit” locks — the user or the DBMS? Are DBMS-placed locks called explicit?

Introduction / Context:
Lock classification helps clarify who requested a lock. Explicit locks are requested directly by user/application commands; implicit locks are acquired automatically by the DBMS while enforcing isolation for DML. This question checks whether you can properly attribute the term “explicit.”

Given Data / Assumptions:

• Examples of explicit locks: LOCK TABLE, SELECT … FOR UPDATE, application-level advisory locks.
• Examples of implicit locks: row/page/table locks acquired automatically during UPDATE/DELETE/INSERT.
• Terminology is consistent across most relational systems.

Concept / Approach:
Locks placed by the DBMS automatically are implicit, not explicit. The statement that “locks placed by the DBMS are explicit” is therefore incorrect.

Step-by-Step Solution:
Identify who issues the request: user command → explicit; system automatic → implicit.Apply to the statement: DBMS-placed locks are implicit.Thus, the statement is invalid.

Verification / Alternative check:
Trace locks during a simple UPDATE under READ COMMITTED; the DBMS acquires and releases locks implicitly without a user lock command.

Why Other Options Are Wrong:
Scope (row/table) and isolation level do not change explicit vs. implicit classification.

Common Pitfalls:
Assuming all locks you see in monitoring were explicitly requested; many are system-driven.

Final Answer:
Invalid statement