In the manufacture of what type of vaccines are organisms treated with chemicals to kill them without changing the antigens?

Inactivated (dead) vaccines are created by treating pathogens with chemicals or physical agents that eliminate the microbe's ability to cause disease while preserving its antigenic properties. This means that the antigens, which evoke an immune response, remain intact and recognizable to the immune system. When an inactivated vaccine is administered, it triggers the immune system to produce antibodies against the pathogen without the risk of causing an infection, as the organisms are dead.

Live vaccines, by contrast, are made from living organisms that have been weakened so they cannot cause disease. Modified live vaccines use a similar approach but involve altering the live organism to reduce its virulence while still keeping it alive to stimulate a strong immune response. Subunit vaccines represent a different approach, as they contain only specific pieces of the pathogen (such as proteins or sugars) rather than whole organisms.

In summary, the correct answer is inactivated (dead) vaccines, as they specifically involve the treatment of organisms to kill them while maintaining the structure of the antigens for effective immune response.