Answer:
B. It's much harder to provide the right atmospheric environment to cultivate obligate anaerobes, so it's been harder to study them.
Explanation:
Obligate anaerobic bacteria are the ones that can grow only in the absence of oxygen. These bacteria do not derive the energy from aerobic cellular respiration and die when exposed to the presence of oxygen.
Owing to their oxygen sensitivity, the culturing of obligate anaerobic bacteria requires special equipment to ensure the absence of oxygen.
The presence of aerobic conditions in laboratories makes their culture and study harder than that of the aerobic or facultative anaerobic bacteria.
