Answer:
A.the flow of energy between organisms in an ecosystem
The combined mass of rock 1 and 2 = 19.28 + 25.3
= 44.58
Difference between rock 3 and combined rocks
= 46.3 - 44.58
= 1.72 grams
therefore, the third rock was 1.72 grams greater than the combined mass of the other two rocks.
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I think it's oxygen and water because they are the substance for cellular respiration.