I think the answer is 3 because natural selection means when someone adapts to their environment
Answer: Ideally, the average heartbeat per minute of an individual is 80 beats per minute.
So if an individual heart's does 80 beats per minutes, then in one hour, that'd be 80 multiplied by 60 minutes, that'd be 4800 beats per hour. In a day, we have approximately 24 hours. Therefore, the total number of heart beat in a day will be 24 multiplied by 4800 which is 115200 heart beats in a day.
The glands of the endocrine system secrete hormones into the bloodstream to maintain homeostasis and regulate metabolism.
