If user-level programs can interfere with privileged programs or services, then changes to system parameters and operating system (OS) integrity issues could result. A privilege escalation attack occurs when a user with limited authority is able to perform actions beyond what he/she has been authorized to do. For example, consider a program scheduling utility that often can run with “system level” authority and allows the user to run a program that his/her security profile ordinarily would not allow. Configuration features of the OS, such as file permissions for critical files, must be set correctly to ensure that privilege escalation attacks are less likely to occur. Choice B is not correct because, while password controls on administrator accounts are very important, ensuring that programs operate within their defined security limits is much more critical. Choice C is not correct because, while file permissions are important, this is only part of the process of ensuring OS integrity. Choice D is not correct because the risk associated with privileged programs or services is more severe than risk related to software that has been compromised or obtained from sources that are not valid.