Question

this image shows someone practicing good hygiene. what does this hygiene practice help prevent? smelling unwanted body odors the transmission of disease exposure to toxic chemicals the spread of common pests

Explanation:

The image shows a person covering their nose/mouth, a hygiene practice (like preventing respiratory droplet spread). Disease transmission (especially infectious diseases) is prevented by such hygiene as it stops pathogens from spreading. Other options: smelling body odors is not a hygiene goal here, toxic chemicals exposure isn't related to this action, and pest spread is unrelated to this personal hygiene act.

Answer:

the transmission of disease