Answer:
C. DDoS
Step-by-step explanation:
DDoS stands for Distributed Denial of Service. It is an an attack which is launched from multiple zombie machines in attempt to bring down a service. The distributed in DDoS signifies the multiple machines used for the attack. The large number of incoming connections/requests overloads the service thereby rendering it unable to fulfil valid requests. In case the attack is originated from only one machine, it is known simply as the Denial of Service (DoS) attack.