Which of the following scenarios indicates a current level that can cause involuntary reactions or injuries?

The scenario that indicates a current level that can cause involuntary reactions or injuries is accurately represented by a current of 5 mA. At this level, electrical currents can stimulate the nerves and muscles, leading to involuntary contractions or spasms. This can potentially result in a person being unable to let go of the source of electricity, increasing the risk of longer exposure.

To provide context, a current flow of 1 mA is generally considered safe and is below the threshold that typically causes any noticeable sensations. A current flow of 3 mA, while it may be felt, usually does not cause significant involuntary reactions or injuries either. In contrast, at 20 mA, the level is high enough to cause significant harm, such as tetany, leading to serious injury or even fatal rhythms in the heart. Understanding these levels is crucial for recognizing the dangers present in electrical environments.