Atmospheric pressure is the pressure of the air outside the body.
Its B.
The correct answer is actually B. Atmospheric pressure refers to the pressure exerted by the weight of the Earth's atmosphere on the objects and surfaces within it. It is the pressure of the air outside the body, which is influenced by factors such as temperature and altitude. To find the answer to this question, you could eliminate options A, C, and D because they all refer to the pressure of air within the body. Then, you can determine that the correct answer is B, as it describes the pressure of the air outside the body.