Final answer:
The greatest security concern with respect to BYOD is the migration of data into and out of the network in an uncontrolled manner, which refers to the transfer of corporate data onto personal mobile devices.
Step-by-step explanation:
The GREATEST security concern with respect to BYOD (Bring Your Own Device) is the migration of data into and out of the network in an uncontrolled manner. This refers to the transfer of corporate data onto personal mobile devices, which can potentially lead to data breaches and unauthorized access. When employees use their own devices for work purposes, it becomes difficult for organizations to maintain control and ensure the security of the data being transferred.