Answer:
Dr. Barnes believes that there is a relationship between smoking and heart disease. This belief is a theory.
Smoking causes heart disease in several ways. The nicotine can directly acts on blood vessels and cause vascular spasms or increased heart rate.
If the lungs were chronically damaged by smoking severe pulmonary hypertension too can cause heart disease.
Explanation:
The word "theory" is defined as an idea or set of ideas that explains something, especially one based on general principles independent of the thing being explained.
Dr. Barnes’s belief about smoking and heart disease fits this definition because it does not rely on any particular evidence to support it, but instead relies on general principles like the effects of nicotine on blood vessels and the heart.
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https://brainly.com/app/ask?q=smoking