You want to retrieve the default security report of nessus. Which of the following google search queries will you use?

The `site:` operator filters results by domain name, not file extension, so `site:pdf` is invalid syntax and will not return PDF files.

`filetype:pdf nessus` omits the quoted phrase `"Assessment Report"` and returns an overly broad set of Nessus-related PDFs, not specifically default assessment reports.

The query `filetype:pdf "Assessment Report" nessus` correctly uses the `filetype:` operator to restrict results to PDF documents and the quoted phrase `"Assessment Report"` to match the exact string found in Nessus default report titles, combined with the keyword nessus to filter for that tool specifically. This precise combination targets Nessus scan output PDFs that have been inadvertently indexed by Google, which is a common Google hacking technique for finding exposed vulnerability reports.

The `link:` operator searches for pages that link to a specified URL, not for file types, making `link:pdf` invalid syntax for retrieving PDF documents.