This is a multiple$-$response inquiry. While each correct response earns credit; response that are not correct yield point deductions for the question.

Which of the following are true regarding lean production systems $($select all that apply$)$:

Select one or more:

a$.$ Even with a lean production system in$-$place; for example, cellular manufacturing, efforts are still made to reduce lot sizes to a single unit.

b$.$ Reduced setup time is a key facet of a lean production system.

c$.$ The transition from traditional processes to lean production systems requires the company's supplier relationships to radically change.

d$.$ A lean production system is designed to expose errors and get them corrected at the source rather than covering them up with inventory or other means.

e$.$ With a lean production system, preventive $($proactive$)$ maintenance of equipment is extremely important.