Where might individuals attempt to hide bombs in a building?

Individuals may attempt to hide bombs in locations such as elevator shafts, closets, and boiler rooms because these areas are often less visible and less frequented by the general public. Elevator shafts are generally enclosed and require specific access, making them less likely to be inspected regularly. Closets, especially those used for storage or maintenance, can easily conceal items without attracting immediate attention. Boiler rooms, usually situated out of sight and often away from main traffic areas, provide a secluded environment where malicious actors can hide dangerous materials without being detected.

In contrast, the other options present areas that either do not offer the same level of concealment or are more likely to be monitored or accessed frequently. For instance, rooftops may be visible and more difficult to access undetected. Storage units, while they may offer some concealment, do not have the same level of accessibility and privacy as the more obscure parts of a building. Emergency exits are critical pathways for evacuating individuals in case of danger; hiding a bomb there poses a higher risk of detection due to the high likelihood that these exits would be frequented during an emergency situation.