Final answer:
option d,Chemical agents are categorized into nerve, blister, and blood agents, based on their effects on the human body.
Step-by-step explanation:
Chemical agents are classified by the U.S. into three categories, which are nerve, blister, and blood agents. These categories are based on how the agents affect the human body. Nerve agents disrupt the transmission of nerve impulses, blister agents cause severe blistering of the skin and mucous membranes, and blood agents interfere with the ability of blood cells to carry oxygen. Each type of agent has a distinct mechanism of action, leading to different symptoms and requiring different medical countermeasures. It's important to understand these categories when discussing chemical warfare or the effects of hazardous chemicals.
The three categories of chemical agents classified by the U.S. are Nerve, Blister, and Blood agents. These categories are used to classify different types of chemical warfare agents based on their mode of action and how they affect the human body.