Which of the Following Would Represent a Systematic Error

Which of the following would represent a systematic error?

A) Eddie regularly overspends,but friends and family bail him out so he always ends up with what he wants.
B) Ellen paid good money for a used car that is in constant need of repair.
C) Sparky determines that he has to reduce donut consumption to lose weight but always ends up eating the ones provided in the break room at work.
D) Clark makes regular math errors at work,sometimes coming out with figures too high,other times too low.