which sort of vulnerability assessment?

Assessing a network from a hacker’s point of view to discover the exploits and vulnerabilities
that are accessible to the outside world is which sort of vulnerability assessment?

A.
Network Assessments

B.
Application Assessments

C.
Wireless Network Assessments

D.
External Assessment

Explanation:

Reference:
http://controlcase.com/managed_compliance_pci_vulnerability_scan.html