A Malicious Hacker Flooded an Online Retailer's Server with Millions

Multiple Choice

A malicious hacker flooded an online retailer's server with millions of bogus service requests. Due to this, the Web site's server was overloaded and the site was unable to service legitimate customer requests. This attack is an example of which of the following security threats?

A) spoofing
B) sniffing
C) phishing
D) denial-of-service