During the Cold War, most research on pilotless aircraft and guided missile systems took place at:

C. a store hiring immigrant workers

Explanation:

As was seen in the text presented in the question above, the NCL promoted a check on the quality of work, wages and environments for workers from social minorities who are easily exploited by their employees, such as women and children. In this case, we can say that the NCL would also oversee the work of immigrants, since this is also a minority that can be exploited and abused by employers, whether in relation to wages, compliance with labor rights, or, the quality of the environment.