Final answer:
When a cell's metabolism increases and oxygen consumption rises, it leads to higher water (H2O) production in a ratio of 2:1 in relation to O2 consumed.
Step-by-step explanation:
As a cell's metabolism increases, there is a corresponding increase in O2 consumption, which is primarily associated with the process of aerobic cellular respiration. During this process, oxygen is used to break down glucose, resulting in the production of ATP and by-products such as H2O (water) and CO2 (carbon dioxide). For each molecule of glucose metabolized, six molecules of oxygen are consumed, and six molecules of carbon dioxide are produced, leading to a ratio of 1:1 glucose to CO2. However, water is also a product of this reaction, and typically, there will be approximately six waters produced for every six oxygen molecules consumed, maintaining a 2:1 ratio of water to oxygen consumed. Therefore, the answer to the student's question is B) H2O (water).