Which of the following is classified as a "Weapon of Mass Destruction" under Title 18 of U.S. Code?

The classification of a "Weapon of Mass Destruction" under Title 18 of U.S. Code specifically includes items that can cause significant harm or destruction on a large scale. Poison gas falls into this category because it is designed to incapacitate or kill individuals through chemical means, often affecting large populations and causing widespread fear and chaos. Its potential for mass harm aligns with the characteristics of a weapon that is classified as a weapon of mass destruction.

In contrast, handguns, knives, and riot control agents are not classified as weapons of mass destruction. Handguns and knives are typically viewed as personal weapons used for self-defense or criminal activity on an individual level rather than large-scale destruction. Riot control agents, while capable of causing harm and used in crowd control situations, do not fit the definition of a weapon of mass destruction as they are intended for temporary incapacitation rather than mass casualties. Therefore, the correct response is poison gas, as it meets the criteria of having the potential to cause widespread harm and chaos through its chemical properties.