What type of attack involves overwhelming a service with traffic to make it unavailable?

The correct choice for the type of attack that involves overwhelming a service with traffic to make it unavailable is the Distributed Denial of Service (DDoS) attack.

A DDoS attack is specifically designed to target the availability of a service by flooding it with excessive traffic, often from multiple compromised devices connected to the internet. This type of attack takes advantage of the fact that the service cannot handle the influx of requests and ultimately becomes unavailable to legitimate users. The distributed nature of the DDoS attack, where multiple sources are used to launch the attack simultaneously, makes it particularly challenging to mitigate and defend against.

In contrast, a Denial of Service (DoS) attack generally refers to a similar concept, but it typically originates from a single source rather than multiple sources. Thus, while both DoS and DDoS attacks aim to disrupt service availability, DDoS is characterized by the distributed nature of the attack.

Man-In-The-Middle attacks are focused on intercepting and altering communications between two parties without their knowledge, which does not relate to overwhelming a service. Credential stuffing attacks involve using stolen credentials to gain unauthorized access to accounts, rather than overwhelming a service.