The correct answer would be Malware. Here is why: Malware refers to a program or script that will affect a target device in a negative way, it cant be hacking because it is a topic, not a tool. Denial of Service is a type of attack that temporarily shuts down servers after a number of requests a device(s) make exceeds the number of requests it can take in a certain amount of time. Spam is either an advertising email from a third party company that bought your email from a list server from a service you gave your info to, like Facebook. Or spam could be a social engineering attack sent by someone trying to harvest your credentials from an email source your email server found untrustworthy.
Please message me if you need any more help with this stuff, I am doing a lot of hacking projects right now and I think I would be a great contact!
