Students hypothesized that adding to a sixth test tube would produce the greatest amount of carbon dioxide

Warm water, yeast, and lactose.

Explanation:

Actually, this question is incomplete because the whole scenario of experiment is not given but the actual scenario is mentioned below.

Some students were doing experiment on cellular respiration and they used the baking yeast to check the fermentation rate. They used different variable with yeast to produce the high amount of carbon dioxide bubbles in a test tube. So, addition of warm water, yeast and lactose will produce the carbon dioxide in greatest amount.

burning of wood and coal

explanation:

the panel also concluded there's a better than 95 percent probability that human-produced greenhouse gases such as carbon dioxide, methane and nitrous oxide have caused much of the observed increase in earth's temperatures over the past 50 years.

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