Which of the following query optimization techniques involves examining only the data that is needed...

The correct answer is C. Indexing documents.

Indexing documents is a query optimization technique that involves creating a data structure that allows faster access to the data in the documents. Indexing documents can reduce the amount of data that needs to be scanned for a particular query, thus improving the performance and efficiency of the query.Indexing documents can also help with searching, sorting, filtering, and aggregating the data in the documents12