Respuesta :
The study of a living being is called biology.
The correct option is A.
A system of a body that helps to prevent the body from getting sick is called the immune system. There are two types of immunity present in the human body. These are as follows:-
- Innate
- Acquired.
The correct answer is skin because it prevents the entry of the pathogen into the body and is present outside the body but the rest of the option is a psychological barrier and is present inside the body.
Hence, the correct answer is A is skin.
For more information, refer to the link:-
https://brainly.com/question/19200238
