Which of the following types of agents causes the most casualties?

Nerve agents are classified as some of the most toxic chemical warfare agents, with the ability to disrupt the nervous system rapidly and lethally. They work by inhibiting the enzyme acetylcholinesterase, which is crucial for nervous system function. This leads to an accumulation of acetylcholine in the synapses, resulting in continuous stimulation of muscles, glands, and central nervous system structures, potentially causing convulsions, respiratory failure, and death within minutes if exposure is significant.

While blister agents can cause severe injuries and long-term health challenges, including severe burns to the skin and damage to the respiratory system, their effects are generally not as immediate or lethal as those from nerve agents. Blood agents, on the other hand, interfere with the ability of blood to transport oxygen, but their use and effectiveness in causing mass casualties are less impactful when compared to nerve agents.

The overall lethality, speed of action, and potential for mass casualties position nerve agents as the leading threat among these chemical agents. Thus, they are recognized as the type of agent causing the most casualties in a chemical warfare scenario.