Which of the following best describes SEO?

SEO (Search Engine Optimization) is a long-term strategy focused on improving a website's ranking in unpaid, or "organic," search engine results. This increased visibility drives more relevant traffic to the site. The other options are incorrect because: "It's a social media campaign to attract influencers" describes a social media marketing tactic, not SEO. "It's a way to increase your email subscribers overnight" is an outcome that might be influenced by various marketing efforts, but it's not the definition of SEO itself, and SEO is rarely an "overnight" process. "It's a form of paid advertising that guarantees website visits" describes Pay-Per-Click (PPC) or other paid search methods, which are distinct from organic SEO.