Which of the following threats involves attackers overloading a server?

The threat that involves attackers overloading a server is the Denial of Service (DoS) attack. In a DoS attack, the attacker aims to make a server or network resource unavailable to its intended users by overwhelming it with a flood of traffic or requests. This excessive traffic can exhaust the server's resources, such as bandwidth, memory, or processing power, ultimately preventing legitimate users from accessing the service.

This type of attack is particularly damaging because it can disrupt operations for businesses, leading to potential financial losses and damage to reputation. The focus of a DoS attack is entirely on making systems unavailable. In contrast, other options, such as brute force attacks, social engineering, and phishing, involve manipulating users or exploiting vulnerabilities to gain unauthorized access or information. These methods do not specifically aim to overload a server in the same way that a DoS attack does, making Denial of Service the correct answer in this context.