In Statistical Process Control (SPC),special or Assignable Causes of Variation

In statistical process control (SPC) ,special or assignable causes of variation:

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