Final answer:
The correct answer is B. A non-functional test during the integration test level, as the test looks to identify performance issues, not functional correctness, and is concerned with the interaction between system components.
Step-by-step explanation:
The test described in the question is a performance test conducted to identify potential network bottlenecks in the interfaces between components of a system. Given that the focus is on the performance, rather than the functional correctness of the system, this test is classified as a non-functional test. Furthermore, it is performed during the integration level when the interaction between different components or systems is examined.
Therefore, the correct answer is: B. A non-functional test during the integration test level.
This kind of testing is crucial for ensuring that all integrated parts of a system work seamlessly together and can handle expected and peak load conditions without significant degradation in performance. By detecting bottlenecks during the integration phase, developers have the opportunity to address these issues before the system goes into production.