In XML Schema (XSD), the schema is primarily composed of which two fundamental constructs?

Introduction / Context:
XML Schemas (XSD) define the structure and data types of XML documents. Understanding the core building blocks of a schema helps you read and design robust XML vocabularies that validate real-world data reliably.

Given Data / Assumptions:

• An XML Schema aims to constrain the content and structure of XML instances.
• We are choosing the two key constructs that XSD uses to declare those constraints.
• We are not dealing with programming terms like methods, nor with relational “tables.”

Concept / Approach:
XML documents consist of nested elements which may carry attributes. XSD mirrors that: it defines element declarations (naming, nesting, occurrence, and type) and attribute declarations (name, type, use). Complex types combine element/attribute content models; simple types restrict scalar values.

Step-by-Step Solution:

Verification / Alternative check:
Any XSD example shows and as the essential declarations, along with types and model groups.

Why Other Options Are Wrong:
Properties/methods: Programming concepts, not schema constructs.
Structure/data: Too vague; XSD expresses structure via elements/attributes and types.
Tables/relationships: Relational terminology, not XML’s tree model.

Common Pitfalls:
Overusing attributes for hierarchical data that should be elements; attributes are best for metadata-like, non-hierarchical properties.

Final Answer:
elements and attributes.