XYZ Inc. modifies a part in such a way that only one supplier is able to produce it$.$ Which of the following if the BEST way for XYZ to reduce the risk of supply chain interruption?

Enter a long$-$term agreement with the supplier to ensure continuity of supply

Request that the supplier produce the part at more than one facility

Revise the specification to allow for other sources of supply

Submit quarterly orders with the suppliers to increase inventory