Final answer:
The correct answer is defense in depth.
Step-by-step explanation:
The correct answer to the question is a) defense in depth. Defense in depth refers to the strategy of having multiple layers of protection in place to safeguard against breaches. When one line of defense is breached, the additional layers provide backup and ensure the overall security of the system. This approach is commonly used in cybersecurity to protect against various forms of attacks. For example, in a network security setup, defense in depth may include using firewalls, intrusion detection systems, antivirus software, and regular software updates.