Answer:
D. He discovered an important mathematical formula.
Explanation:
Pythagoras was a Greek philosopher and mathematician considered the first pure mathematician. Contributed significantly in the advance of Hellenic mathematics, geometry, arithmetic, derived particularly from the numerical relationships, and applied for example to the theory of weights and measures, to the theory of music or astronomy. Regarding music, its concepts of I, IV and V, were the fundamental pillars in the Greek harmonization, and are those used today. He is the founder of the Pythagorean School, a society that, although it was predominantly religious in nature, was also interested in medicine, cosmology, philosophy, ethics and politics, among other disciplines. Pythagoreanism formulated principles that influenced both Plato and Aristotle and, more generally, the later development of mathematics and rational philosophy in the West.