What should be ensured about vent holes in acquired structures for live fire training?

The correct choice emphasizes the importance of preparing vent holes in acquired structures specifically for live fire training scenarios. Precut holes allow for better control of the fire conditions during training exercises. Properly made vents can help in controlling smoke, heat, and gases, enhancing safety for both the trainees and instructors. Additionally, precutting ensures that the holes are located strategically, minimizing the risk of unexpected structural failures during training.

In contrast, leaving vent holes open at all times could lead to uncontrolled spread of fire and dangerous situations, while sealing them permanently or opting not to use them could prevent essential ventilation needed for safety and realism in training. Therefore, the necessity for precut and temporarily closed vent holes is crucial for maintaining a safe and effective training environment.