which type of barrier are coughing and sneezing?\n psychological\n chemical\n biological\n physical

Brief Explanations:

Coughing and sneezing expel foreign - substances and pathogens from the body. They are physical actions that act as a first - line defense, pushing out potentially harmful particles. They are not psychological (related to mental processes), chemical (involving substances like enzymes or antibodies), or biological (in the sense of cellular or organism - level biological mechanisms other than physical expulsion).

Answer:

D. physical