Stirred- tank bioreactors have been designed for
Product purification
Addition of preservatives to the product
Oxygen availability throughout the process
Ensuring anaerobic conditions in the culture vessel
As we have already discussed in Bioreactors -
A stirred-tank reactor is usually cylindrical or with a curved base to facilitate the mixing of the reactor contents. The stirrer facilitates even mixing and oxygen availability throughout the bioreactor. Hence, the correct option is (c).