Unfortunately，attackers have many options of attacks to perform against their targets. Which of the following is considered a denial-of-service （DoS）attack？（）

A.Pretending to be a technical manager over the phone and asking a receptionist to change their password
B.While surfing the web，sending to a web server a malformed URL that causes the system to consume 100 percent of the CPU
C.Intercepting network traffic by copying the packets as they pass through a specific subnet
D.Sending message packets to a recipient who did not request them，simply to be annoying