In the world of search engine optimization, search results are unpaid listings that appear solely because of their relevance to the search terms entered when conducting an Internet search.

"Organic" is the correct answer for the above question.

Explanation:

The Organic search is used in the search engine after making the query of one or more string. It means that when any user searches a query after combining the one or more string on it then it comes in the term of Organic search.It gives the specified result for any search. So many users of the search engine Optimization were using this technology.The above question asked about the method, which is used in optimization and gives the result slowly but good. This method is known as "Organic search".