Answer:
B) Valves closing
Explanation:
A healthy heart makes a lub-dub sound with each beat. This sound comes from the valves shutting on the blood inside the heart. The first sound (the lub) happens when the mitral and tricuspid valves close.
The respiratory system can be damaged from smoke inhalation and tar buildup from the chemicals used in tobacco, which can also harm the heart and blood vessels. Two conditions that can be caused from smoking are Heart Disease and Lung Cancer.
Answer: General health apps are used more often than medical apps.
Explanation:
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