What question should you consider to improve your website's SEO performance?

The question regarding whether your key landing pages have been indexed is fundamental to improving your website's SEO performance. Indexing by search engines is crucial because it determines whether your pages will appear in search results. If a page is not indexed, it essentially remains invisible to users searching for relevant content, meaning you could miss out on valuable organic traffic. Ensuring that your key landing pages are indexed allows search engines to crawl them, evaluate their content, and display them to users, which is the primary goal of SEO.

While the other options pertain to important aspects of digital marketing, they do not directly address the foundational elements of SEO in the same way. Implementing social media advertising, setting up email marketing campaigns, and optimizing for mobile users indeed contribute to an overall digital strategy. However, without proper indexing, these efforts may not yield the desired SEO benefits since search engines won't recognize the content of your site that could be promoted through those channels. Therefore, confirming that your pages are indexed is a critical first step in SEO optimization.