If you have a distension of the stomach that can mean one 4 or more things. you ate something bad or old. you spun around in circles and feel like throwing up. you get a headache and you feel sick from your stomach. you got a stomachache
The remains of fossils give scientists clues as to what the world may have been like a long tome ago. If fish fossils are found on the side of a mountain, there may have been a lake there. If a skeleton is found, they can decide what creature it was.
Answer:
immune system
Explanation:
The adaptive immune system reacts specifically to pathogens (germs). It is able to recognize attacking pathogens and fights against certain antigens or foreign substances. The next time a known antigen is encountered, the adaptive immune system can respond faster.