Final answer:
Use the sys.server_file_audits system view to obtain a list of all audits that write data to a file target, as it provides a row for each server audit definition configured for file targets.
Step-by-step explanation:
If you want the list of all audits that write data to a file target, the correct system view to use is sys.server_file_audits. This view provides a row for each server audit definition that is currently configured to write to a file target. It will include important information about the file audit, such as the audit's name, the file path where the audit data is written, and other relevant configuration details. The other system views listed are useful for different auditing aspects: sys.server_audit_specifications_details provides details on the server audit specification, sys.server_audit_specifications displays the server audit specifications, and sys.server_audits gives information about the server audit but it does not focus specifically on audits that write to file targets.