Answer:
c. oxygen for medical use
Explanation:
Beer is made by the fermentation of starch into wort (a sugary liquid) and then converting the wort into beer by the addition of yeast. Fermentation is an anaerobic process (breakdown of bio material in the absence of air) where energy is extracted from carbohydrates.
Ethanol fuels is also made in the same way i.e., through fermentation process where sugars are converted to cellular energy and produce Ethanol and Carbon dioxide.
Oxygen for medical use is made by separating it from air by the cryogenic distillation process or a vacuum swing adsorption process. In these processes no respiration takes place.
The process of bread making involves a step called leavening. Here yeast is added. The yeast carries out the process of fermentation discussed above.
