Final answer:
At least two qualified persons should be in attendance at a transfer operation to ensure safety and efficiency.
Step-by-step explanation:
In a transfer operation, the number of qualified persons that must be in attendance will vary depending on the specific requirements and circumstances. Generally, it is recommended to have at least two qualified persons present to ensure safety and efficiency. These qualified persons may include trained professionals, such as logistics experts or security personnel, who are knowledgeable about the transfer process and can handle any unforeseen issues that may arise.