First, read the passage; then, answer the question that follows. The Ins and Outs of Bellybutton Lint, by Joel Guthrie

Some scientists gaze into outer space to look for answers. Some scientists seek answers in the depths of the sea. When Georg Steinhauser wanted answers, he looked within himself. Well, he looked within his bellybutton to be exact. The Austrian chemist spent three years researching the contents of his navel and the navels of others. He has solved one of life's greatest mysteries. We now know exactly what bellybutton lint contains!

Steinhauser presented his findings in the online version of the journal Medical Hypotheses. The Vienna University scientist analyzed over 500 samples to determine the exact makeup of the lint. As suspected, most of the lint was made up of cotton from clothing. The fabric pieces are not alone, though. Steinhauser found that the average bellybutton also contained pieces of dead skin, sweat, dust, and fat.

Steinhauser's notes also explained how lint accumulates. Stomach hairs tend to grow in a circular pattern around the bellybutton. The hairs act like small hooks, capturing and holding contents within. Shaving stomach hair can lead to a lint-free bellybutton, but don't act too hastily. Although the contents of your navel may be a nuisance, research suggests that lint has a purpose. It is nature's way of protecting your bellybutton from germs and unwanted objects.

Question: All of the following details should be included in a summary of The Ins and Outs of Bellybutton Lint, except

a
the name of the chemist, Georg Steinhauser, and what he was researching - bellybutton lint.
b
that Steinhauser found fabric, dead skin, sweat, dust, and fat in the bellybutton lint.
c
over 500 samples of lint from various people's bellybuttons were analyzed.
d
the author's name, Joel Guthrie, and title of the article, "The Ins and Outs of Bellybutton Lint".