The trachea has an epidermis layer that acts as a barrier and protects organs from things such as : dust, mucus and also pathogens Hope that helps :)
B is the answer to your question.
Answer:
With media exposing a lot of water companies day by day, the concerns related to bottled water are increasing at a high rate.
In some cases, it has been proved that bottled water is actually tap water. Some other cases prove that bottled water companies draw underground water and transport it away without testing of the water. Ground source of water might be considered to have pure water but it still can have mud of infectious agents. Hence, it should be properly tested before sending them to the market.
