What must an EPUB conformance requirement include?

The correct response highlights the essential properties required for EPUB conformance, specifically the "conformsTo" property and the "a11ycertifiedBy" property. These elements are integral to ensuring that the EPUB file adheres to specified accessibility standards and guidelines.

The "conformsTo" property indicates which accessibility standard the document meets, providing clarity and assurance that it follows necessary protocols to be usable by individuals with disabilities. This aspect is crucial for compliance and helps users identify the EPUB's alignment with established guidelines, enabling better accessibility outcomes.

The "a11ycertifiedBy" property is equally important as it identifies the individual or organization that has verified the document's compliance with these standards. This certification adds a layer of credibility and accountability, reassuring users that the EPUB has undergone appropriate assessments for accessibility.

In contrast, other options, such as including a table of contents and an index, while valuable for user navigation, do not specifically align with the conformance requirements needed to address accessibility standards. Similarly, an author and description are essential metadata for a document but do not directly pertain to the adherence of accessibility specifications. Lastly, providing multiple versions of content is not a requirement for EPUB conformance; it's more related to content delivery strategies rather than compliance with