The Web Content Accessibility Guidelines (WCAG) define three levels of conformance for web content accessibility:

Level A (Single A) is the minimum level of compliance.

Level AA (Double A) is the standard recommended for most websites, balancing accessibility and design.

Level AAA (Triple A) is the highest and most comprehensive level of accessibility, covering the widest range of needs.

There is no such level as “Quadruple A (AAAA),” making option D invalid.

Thus, WCAG Triple A (AAA) promises the most accessible content, even though it may not always be practically achievable for all types of content.