The final group may be identified as the meteoroid$/$space dust group. This group of physicians produces insignificant profit, or even loss due, to complete unresponsiveness to salespeople's efforts and promotional campaigns. They are accustomed to prescribing certain medications and are not open to learning about new discoveries in the pharmaceutical industry. The best strategy regarding this group is to leave it to turn into space dust and move on$.$ Which physician belongs to this group? $($Use the above application of the activity$-$based costing ABC method to customer physicians to determine your answer.$)$

Customer A

Customer B

Customer D

Customer C