Which of the following statements is NOT true with respect to database…

Concept: normal forms nest strictly — every relation in 3NF is also in 2NF, every relation in BCNF is also in 3NF, and every relation in 4NF is also in BCNF. Each step forward adds exactly one extra restriction on top of the previous one: 2NF forbids a non-key attribute depending on only part of a composite key; 3NF additionally forbids a non-key attribute depending transitively on another non-key attribute; BCNF additionally requires every non-trivial functional dependency to have a superkey as its determinant; and 4NF additionally requires that same superkey-determinant condition for every non-trivial multi-valued dependency. Because a stricter form only adds a restriction and never removes one, its set of possible anomalies can only be a subset of the weaker form's. Concretely, each comparison below is between the SAME relation decomposed only as far as the weaker normal form versus decomposed further to satisfy the stricter one — the standard convention such comparisons always intend — so a claim like "a 3NF table has fewer anomalies than a 2NF table" means: whatever anomaly a 2NF-only decomposition of that relation still carries, decomposing it further to 3NF removes, never adds.

Application: check each statement against that nesting property.

• "A 4NF table is more immune against logical inconsistencies than a 3NF table." — holds: 4NF requires every non-trivial multi-valued dependency to have a superkey determinant, in addition to everything 3NF already requires, closing a redundancy path that 3NF's transitive-dependency rule alone does not address.

• "A 3NF table will have fewer anomalies than a 2NF table." — holds: 3NF is 2NF plus the extra no-transitive-dependency restriction, so a 3NF table's anomaly set is a subset of a 2NF table's.

• "A 3NF table is more vulnerable than a 2NF table." — does not hold: by the same nesting property just used above, a 3NF table's anomaly set can only be a subset of a 2NF table's, so it can never be more vulnerable. This is the statement that is NOT true.

• "A database is said to be in 3NF if all its tables are in 3NF." — holds: a normal-form label applied to a whole database is standard shorthand for every one of its tables independently satisfying that normal form.

Cross-check: three of the four statements are direct instances of the same nesting rule (a stricter form's anomaly set is a subset of the weaker form's); only the claim that 3NF is more vulnerable than 2NF contradicts that rule, confirming it as the one statement that is NOT true.