B. Bacteria which can complete their life cycle without water
C. Colonies of unicellular bacteria
D. Bacteria which can complete their life cycle without oxygen
Explanation
Anaerobic Organisms: Anaerobic organisms, including certain bacteria, are those that do not require oxygen for growth and survival.
Oxygen Toxicity: Some anaerobic bacteria are highly sensitive to oxygen and cannot tolerate its presence, while others can tolerate small amounts of oxygen.
