Sequential processing is characterized by
  a.  a pattern where partially completed units are worked on simultaneously.
  b.  a pattern where different partially completed units must pass through parallel processes before being brought together in a final process.
  c.  a pattern where partially completed units must pass through one process before they can be worked on in later processes.
  d.  a pattern where partially completed units must be purchased from outside suppliers and delivered to the final process in a sequential time mode.
  e.  none of the above.