Which type of Chemical Warfare Agent is most likely to cause immediate effects on breathing?

The correct answer is the choking agent. Choking agents are primarily designed to cause damage to the respiratory system by irritating the lungs and leading to difficulty breathing and potential suffocation. When inhaled, these agents can result in immediate and severe respiratory distress, making their effects noticeable almost instantly.

Choking agents include substances like chlorine gas and phosgene, which disrupt normal breathing by causing inflammation and fluid accumulation in the lungs. This physiological impact can result in rapid onset symptoms, which is why they are the most likely to cause immediate effects on breathing among the options listed.

While nerve agents and blood agents also pose significant threats to human health and can affect respiratory function, they do so through different mechanisms and may not produce immediate symptoms related specifically to breathing. Blister agents primarily target the skin and mucous membranes rather than the respiratory system directly, leading to a different spectrum of effects.