Source code for the software must be placed in escrow is the most important requirement to include in the vendor contract to ensure continuity. Source code is the original code of a software program that can be modified or enhanced by programmers. Placing source code in escrow means depositing it with a trusted third party who can release it to the customer under certain conditions, such as vendor bankruptcy, breach of contract, or failure to provide support. This can help to ensure continuity of the software product and its maintenance in case of vendor unavailability or dispute. The other options are less important requirements to include in the vendor contract, as they may involve support availability, disaster recovery plan, or staff training. References:

CISA Review Manual (Digital Version), Chapter 5, Section 5.51

CISA Review Questions, Answers & Explanations Database, Question ID228