Choice "D" is correct. Just-in-time is not designed to produce variability but to accommodate production cycles and reduce carried inventory by delivering goods to the manufacturing process just-in-time.
Choice "c" is incorrect. Cost reductions from reduced inventory are a benefit of just-in-time.
Choice "b" is incorrect. A reduction to work-in-process because of reduced materials pending processing is a benefit of JIT.
Choice "a" is incorrect. Overall improvements in effectiveness, efficiency and quality are benefits of JIT.
