Final answer:
The answer to the question is C. Ocean acidification, which is the result of atmospheric carbon dioxide dissolving in ocean water and lowering the pH levels, potentially affecting marine life.
Step-by-step explanation:
The question asks which outcome would most likely result from an increase in carbon dioxide levels, independent of any change in temperature. The answer is C. Ocean acidification. This process occurs when atmospheric CO2 dissolves in ocean water, leading to a decrease in pH levels, which can adversely affect marine life, particularly organisms that rely on calcium carbonate to produce their exoskeletons, such as corals. Increased plant growth may be a secondary effect of higher CO2 levels, but it's not directly referenced as the primary outcome independent of temperature changes in the provided information.