Louis Pasteur performed a series of experiments that disproved spontaneous generation. What aspect of his design represented the experimental part of the test

Two different kinds of flasks were used - regular and swan-necked

Explanation:

In his experimental design, Louis Pasteur used tow flasks. One of the flask was regular flask and the other was swan necked. He used these flasks to boil a meat broth. In the swan neck flask, air could enter but microorganisms could not. As a result, there was no grown seen in that flask. In the regular flask, microorganisms could enter and they spoiled the meat. Hence, the two different types of flasks were his experimental design.