For a requirement stating that the user interface needs to be accessible to the visually impaired, the best-derived requirement is that the user interface has voice activation. Voice activation directly addresses the needs of visually impaired users by allowing them to interact with the software using voice commands instead of relying on visual cues. This makes the interface more accessible and aligns with accessibility standards such as the Web Content Accessibility Guidelines (WCAG) and Section 508 of the Rehabilitation Act, which mandate that technology be accessible to people with disabilities.