Answer:
The correct answer would be "if oxygen is allowed to be present the fermentation process will not happen"
Fermentation refers to the biochemical process by which substances are broken down with the help of microbes such as bacteria, yeast et cetera.
It typically takes place in absence of oxygen.
In presence of oxygen, the yeast would be switched to aerobic respiration due to which the desired products such as wine, alcohol, acetic acid et cetera would not form.
Thus, vats should be sealed in order to prevent the entry of oxygen.
