The Disadvantage for a Manufacturer in Using Only One Vendor

The disadvantage for a manufacturer in using only one vendor to supply a critical raw material, process material, component part, or fabricated part is the fact that

A) the quality may not be as good as other vendors could provide
B) the manufacturer's production schedule may be interrupted if the vendor cannot meet the manufacturer's supply needs
C) the manufacturer would not obtain as good a price as if multiple vendors were used
D) the manufacturer can no longer negotiate price