ApexTech, a cybersecurity consultancy, was approached by a large energy conglomerate to assess the robustness of its energy grid control systems. The conglomerate Is transitioning from traditional systems to a more interconnected smart grid. ApexTech proposed a penetration test to identify potential vulnerabilities in the new setup. The firm provided four methodologies it could employ to assess the system's vulnerabilities comprehensively. The energy conglomerate must select the approach that would be MOST revealing and beneficial in identifying vulnerabilities in the context of its transitioning infrastructure: