A. Decrease in the combustion of fossil fuels in the summer months.
B. Carbon dioxide dissolves in the oceans more rapidly during the summer months.
C. More carbon dioxide is fixed through photosynthesis in the northern hemisphere during the summer.
D. More carbon dioxide is released in the summer in the northern hemisphere.
参考答案:
C
本题详细解析:
Explanation:
In the summer months, the rate of photosynthesis increases in the northern hemisphere and more atmospheric carbon dioxide is used to make organic compounds by photosynthesizing organisms such as green plants and trees.
There is no substantial decrease in the consumption of fossil fuels during the summer, which could explain the fluctuation of carbon dioxide in the atmosphere (Choice A). Carbon dioxide dissolution in the oceans cannot account for the fluctuations either (Choice B).
The rate of photosynthesis is on average greater than the rate of respiration in the northern hemisphere during the summer which means more carbon dioxide is absorbed, not released at this time (Choice D).
