True. remember the phrase, use it or lose it?
Cardiovascular system has to do with the heart, so anything to reduce the risk of that system (including the heart, bloodstream etc.) would be the answer for you. So just using Process of elimination:
A) Has to do with external exposure. <em>No</em><em />
B) Keeping hands clean <em>No</em><em />
C) Avoiding cigarette smoke <em>Yes</em>
D) Keeping your vaccinations up to date <em>No</em><em />
So your answer is C.
Usually teens should get 13 hours of sleep eat healthy exercise regularly
The answer is D (frequency, duration, and intensity