Biology

In the absence of oxygen, bacteria (and some other cells) can switch to fermentation. If the pH of the solution is decreasing, it is likely due to the production of lactic acid as a byproduct of lactic acid fermentation. As lactic acid accumulates, it releases H⁺ ions, which lowers the pH, making the environment more acidic.

The other options are incorrect:

Option A: Aerobic respiration requires oxygen, which is not available in this scenario.

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