The outermost layer of a blood vessel is known as
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The tunica intima
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The tunica media
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The tunica externa
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The pericardium
C
Correct answer
Explanation
The tunica externa, also known as the tunica adventitia (or adventitia), is the outermost layer of a blood vessel, surrounding the tunica media. It is mainly composed of collagen and is supported by external elastic lamina.