Which of the following tools is used for vulnerability scanning and calls Hydra to launch a dictionary attack?

Whisker (spelled 'Whishker' in the question) is a CGI scanner focused on web server vulnerability enumeration and does not integrate with Hydra for dictionary attacks.

Nessus, developed by Tenable, is a full-featured vulnerability scanner that supports credential testing plugins which invoke Hydra - a parallelized login cracker - to perform dictionary attacks against services such as FTP, SSH, and HTTP. This integration allows Nessus to test for weak or default credentials as part of an authenticated or unauthenticated vulnerability scan.

SARA (Security Auditor's Research Assistant) is a Unix-based network analysis tool derived from SATAN that performs host and service vulnerability checks but does not specifically call Hydra for dictionary attacks.

Nmap is primarily a network discovery and port scanning tool - while it has the Nmap Scripting Engine with some brute-force scripts, it is not a vulnerability scanner and does not natively call Hydra as part of its scanning workflow.