Which of the following attacks requires the attacker to be in close physical proximity to the target?

The answer is C, Close-In Attack, because this type of attack specifically involves an attacker needing to be within a short distance from the target in order to execute the attack effectively. Close-In Attacks are often characterized by techniques such as eavesdropping on wireless communications, physically accessing a device to steal data, or planting devices in close proximity to gain access to networks or information.

In contrast, Passive Attacks generally do not require physical presence; they involve monitoring and collecting data without altering the system or the data, which can often be done from a distance. Active Attacks involve interference or tampering with the data transmission, but they can also be launched remotely, without the necessity for physical proximity. Disruption Attacks can be executed remotely or from afar and primarily focus on interrupting services or delivering denial-of-service attacks without needing to be near the target.

Therefore, Close-In Attack is the only type in which the effectiveness depends on the attacker's physical location relative to the target.