To be honest, I'm not that sure on which one it is, but given choices lead me to think is the nervous system, probably because that's the reason our bodies are functioning, and compared to all other systems, the brain and the nervous system are needed for survival, otherwise you wouldn't be living.
True
If a doctor is not notified, the chronic injury/condition could worsen
<span>In an event of a rattlesnake bite, keeping the person bitten to calm down is the 1st thing to do. When the venom reaches the heart of the victim, it could lead to a fatal death. So by calming down, the circulation of blood is prevented to rise. After which, they directly cut an "x" at the middle of the bite marks and suck out blood as many as possible hoping that the venom is also sucked out too. This was an old technique used in the Oregon trail and may not be the best technique there is nowadays.
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If an organism can adapt to its environment, it is more likely to survive because it changes and adheres to things