B. Style
A writers choice of words, or diction, mostly affects an essay’s style.
The tunica externa (New Latin "outer coat"), also known as the tunica adventitia (New Latin "additional coat")(or adventitia for short), is the outermost tunica (layer) of a blood vessel, surrounding the tunica media. It is mainly composed of collagen and, in arteries, is supported by external elastic lamina.