Final answer:
Oxygen is required for brain cells to produce sufficient levels of ATP. Lacking oxygen, brain cells cannot maintain the high and steady production necessary for brain function, leading to possible brain damage or death within minutes. hence option A is the correct answer.
Step-by-step explanation:
When people compete to see who can hold their breath longer underwater, it can be harmful because brain cells are particularly sensitive to a lack of oxygen. If the brain does not receive enough oxygen, the cells cannot make enough ATP (adenosine triphosphate), which is essential for the energy needs of the cell. Without ATP production, brain damage can occur in a matter of minutes, emphasizing the importance of oxygen for cellular respiration and survival.
In the context of the question, the correct answer is: Without oxygen, brain cells Cannot make enough ATP (Answer A). This is because oxygen is a vital reactant in the aerobic stages of cellular respiration, a process that generates ATP. Without sufficient oxygen, cells resort to less efficient energy production pathways that do not require oxygen, such as fermentation, leading to a build-up of lactic acid and only a small amount of ATP.