The success of Pasteur’s experiment was a result of his luck: he happened to use an easy-to-kill yeast and not hay bacillus. Mendel’s experiments also worked because of luck: “luck had been with him his choice of which particular traits to study.” He was spared failure because he picked traits that produced logical results. Luck, therefore, is what makes Pasteur’s use of a certain yeast comparable to Mendel’s choice of traits to study, which is C.