Answer: The correct answer for the blank is-
B.anaerobic.
Step-by-step explanation:
Anaerobic organisms are those organisms that do not require free oxygen for their growth and survival. In other words, these organisms can grow in the absence of free oxygen that is in the absence of oxygenated environment.
Example - Certain bacteria (such as from the genera Clostrodium, Fusobacterium, Actinomyces etc), some protozoan and some worms are Anaerobic organisms.