Final answer:
Companies are mandated by regulations and industry standards to conduct independent security reviews, leading to the hiring of security assessors and penetration testers.
Step-by-step explanation:
The question asks which external pressure causes companies to hire security assessors and penetration testers. The correct choice from the given options is D. Regulatory insistence on independent reviews. Companies are often required to adhere to industry standards and regulations that mandate third-party security assessments, making it an external pressure that influences the need to hire security professionals. This can range from compliance with standards like the Payment Card Industry Data Security Standard (PCI DSS) to legislation such as the General Data Protection Regulation (GDPR) or the Health Insurance Portability and Accountability Act (HIPAA).
Regulatory compliance ensures that companies maintain the integrity, confidentiality, and availability of information, which is essential in protecting against data breaches and maintaining customer trust. Independent security reviews are crucial for identifying potential security weaknesses that internal staff may overlook due to familiarity or lack of specialized expertise. This ensures that security measures are effective and can prevent incidents like the massive data breach experienced by Target in 2013 due to misinterpreted security signals.
Final answer in 20 words: Companies face the external pressure of regulatory compliance requirements to hire security professionals for independent reviews.