What was the function and importance of s-necked flasks in louis pasteur's experiments in disproving spontaneous generation?

Louis Pasteur discovered heating as a process of removing the number of bacteria present in a liquid best known as pasteurization. He used S-necked flasks in his experiment in order to permit the air to pass into the flask, such that it maintains any airborne microorganism that contaminate the broth at the same time.

The correct answer is b