Current levels from which range can cause extreme pain and possibly respiratory arrest?

The correct answer, indicating a current range of 50 to 150 milliamperes (mA), is significant due to the physiological effects electrical currents can have on the human body. At this level, the risk of severe consequences, such as extreme pain and possibly respiratory arrest, dramatically increases.

Currents in this range can interfere with the normal electrical activity of the heart and other vital organs. For instance, currents above 50 mA are known to cause ventricular fibrillation, which is a life-threatening condition where the heart quivers instead of pumping effectively. It can disrupt the respiratory muscles, leading to respiratory arrest as the body's ability to ventilate efficiently becomes impaired.

Additionally, the sensation of pain increases significantly as the current levels rise, with higher ammeter readings correlating with the severity of discomfort experienced. Thus, 50 to 150 mA is a critical threshold where the risks to life and health become much more severe, necessitating immediate medical response when such currents are involved.