Which of the following requires oxygen to survive?

Obligate aerobes are organisms that require oxygen for their survival and growth. They rely on aerobic respiration to produce ATP, which is the energy currency of cells. In the presence of oxygen, obligate aerobes efficiently harvest energy from nutrients through processes such as glycolysis, the citric acid cycle, and oxidative phosphorylation. Without oxygen, these organisms cannot sustain their metabolic processes, leading to the inability to survive.

Facultative anaerobes, on the other hand, can survive with or without oxygen. They have the ability to switch between aerobic respiration when oxygen is available and fermentation or anaerobic respiration when oxygen is absent. Obligate anaerobes, conversely, cannot tolerate oxygen at all; oxygen for them is toxic, and they rely entirely on anaerobic processes. Aerotolerant anaerobes can survive in the presence of oxygen but do not use it for metabolism; they only engage in fermentation regardless of the oxygen availability.

Thus, it is the obligate aerobes that specifically require oxygen for their survival, making this choice the correct answer.