Which of the following statements is correct (10 points)? (a) There are simple countermeasures for botnets that communicate with a C&C server with a fixed address (b) The common payload of spyware malware is information theft that compromises the integrity of the victim system (c) A hacker needs to put time and effort to implement a backdoor (d) As malware is mostly a compromised software program, it cannot physically damage the victim computer.