By the unequal heating of earths surface
C is the answer.We are using to classify organisms beyond molecular setting not by the physical structure.note-applicable for this question only
Incorporating basic life support, the first thing one should do is survey the scene. Look for any obstacles that will make the response difficult such as shattered glass, fire, etc. Second, call emergency hotline (usually it's 911 but it may differ from other countries). If you are a certified basic life support provider, then continue with the next steps. Next step would be checking the patient's airway, breathing, and circulation (ABC) by checking the if there is blocking the airway, or if the patient can breathe spontaneously, as well as the pulse. Next step would be assess if the patient as a cervical fracture as this should be handled carefully. If the patient is not breathing or has no/decreased pulse then proceed with doing CPR until help arrives.
