In statistical process control (SPC), special or assignable causes of variation: A. are of secondary importance in quality control procedures used to detect and eliminate variation. B. are outside and nonrandom problems such as the breakdown of machinery, material variation, or human error. C. can be present in a process that is fully capable of meeting specifications consistently. D. have everything to do with the underlying process and can only be eliminated by changing the process. E. are intrinsic to the process and will always be there unless the process is changed.