Final answer:
The question does not provide enough context to determine the exact time when breaks are not allowed on a 2nd shift. Traditionally, breaks might not be allowed during periods of high productivity or critical operations; however, without specific company policies, any of the provided periods could be correct. The traditional understanding might point to 2pm-4pm as the most likely time.
Step-by-step explanation:
The provided information does not directly indicate when breaks are not allowed on a 2nd shift, such as the shift lasting from 3:30pm-6:30pm, 4pm-7pm, 5:30pm-6:30pm, 2pm-4pm, etc. However, using historical context and common working conditions, it is likely that breaks would not be allowed during the most productive or critical working hours, where workflow might be seriously interrupted. This would likely be during periods when breaks can cause a significant slowdown in operations or when work demands are at their peak. Traditionally, shifts of ten to twelve hours with strict break schedules in factories didn't allow for flexibility.