A supply chain is essentially a sequence of linked:

answer c : suppliers and customers_____________________________

supply chain is essentially a sequence of linked between supplier and manufacturer.

>>>>>>>>>>>  C. suppliers and customers  >>>>>>>>>>>>>

.......... . . . .

.......... . . . ..

C. suppliers and customers...... . . . .

D. warehousing and wholesaling units^^^^^^^^^^^^^^^^^^

C. suppliers and customers

B. supplier and manufacturer sequence flow is as below

Supplier ---> Manufacturer --->> distributor --->>>> Customer.

D. warehousing and wholesaling units <<<<<<<<<Answer

c>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

answer is D. 

Manufacturer and customer , are out of supply chain management 

otherwise warehousing and wholesaler unit are the one who attentively coordinated the supply data and who essentially need attentitive sequences