When a flaw in Industrial control (ICS) software is discovered, what is the GREATEST impediment to deploying a patch? Please provide the answer with explanation. Thanks
A. Many IG systems have software that is no longer being maintained by the vendors.
B. Compensating controls may impact IG performance.
C. Testing a patch in an IG may require more resources than the organization can commit.
D. vendors are required to validate the operability patches.