Answer:
The current population of earth is 7.9 billion if that is what you were asking.
Avoiding secondhand smoke can help prevent lung cancer.
Answer:
Once a year
Explanation:
Many people go get an annual physical. Going only when you feel sick will not show your overall health and the changes in your body. It is not needed to go to the doctor's twice a year unless you are immunocompromised, once a year will suffice.
Answer:
The answer is A. Endocrine
