Choose the following statements which are correct with respect to continuous culture systems:

(A) In simple stirred tank bioreactor, the stirring happens through sparging of air bubbles

(B) Bioreactor has an agitator system, oxygen delivery system and foam control system

(C) Sampling ports provides vents to withdraw small volumes of culture periodically

(D) Culturing in bio reactors is classified as downstream processing

Choose the correct answer from the options given below: