Answer:
parallel; unitary
Explanation:
There are two types of processing: unitary processing and parallel processing.
In unitary processing, the person uses neural processing and do not require any other subsystem while in parallel processing, the person uses a computing system to evaluate the complexity of the task that reduces reducing the amount of time for processing.
In the given example, Brad relies more on parallel processing and uses computing system to scan the bags as he/she is new while Christine uses unitary processing as she was experienced, so did not require any subsystem.
Hence, the correct answer is "parallel; unitary".