How do search engines determine page authority?

Search engines determine page authority primarily by analyzing various factors that contribute to the trustworthiness and relevance of a webpage. Backlinks are critical; they serve as endorsements from other websites, indicating that the content is valuable and worth referencing. High-quality content plays a significant role as well, as search engines prioritize pages that provide useful, well-researched, and engaging information to users. User engagement metrics, such as time spent on the page, bounce rates, and interactions, also inform search engines about the content's value, as pages that keep users engaged are often more authoritative.

While the other options touch upon website performance or design aspects, they do not directly correlate to how search engines evaluate authority. Factors like loading time and server location can influence user experience, but they don't fundamentally affect a page's authority. Likewise, assessing the user interface or the number of ads does not directly reflect the quality or trustworthiness of the content, which is central to authority assessment by search engines. Thus, the comprehensive evaluation of backlinks, content quality, and user engagement makes option B the most accurate response in context.