Collections terminology — ordered vs. unordered.\n\n"An ordered collection of elements of the same type is called a set."

Introduction / Context:
Many data models distinguish between sets and lists/sequences. Sets are fundamental in mathematics and computer science and are characteristically unordered and duplicate-free. This question checks your ability to differentiate collection types by ordering and homogeneity.

Given Data / Assumptions:

• “Ordered collection” implies elements have a defined position or index.
• “Same type” means homogeneous elements, which can be true for sets or lists.
• Terminology is broadly consistent across math, programming, and databases.

Concept / Approach:
A set is unordered and disallows duplicates. A list/sequence/array is ordered and typically allows duplicates. Some systems implement bags (multisets) which are unordered but allow duplicates. Therefore, calling an ordered same-type collection a “set” is incorrect; the appropriate term is “list,” “array,” or “sequence.”

Step-by-Step Solution:

Verification / Alternative check:
In SQL, a table represents a set of rows (logical unorderedness). Ordering is applied via ORDER BY; without it, the result has no guaranteed order. In programming languages, arrays/lists preserve insertion or index order, unlike typical set structures.

Why Other Options Are Wrong:

• Claiming sets are ordered reverses the definition.
• Tying validity to SQL, keys, or duplicates confuses orthogonal properties.

Common Pitfalls:
Assuming physical storage order equals logical order; believing primary keys impose ordering; conflating multisets (bags) with sets.

Final Answer:
Invalid (a set is unordered; an ordered same-type collection is a list/array/sequence)