If the dogs are different breeds, their activity levels could be different because of their breed and not the caffeine. The correct option is A.
<h3>Reliability of experiments</h3>
In order for the outcomes of scientific experiments to be reliable, constant variables should be kept constant.
In the illustrated experiments, the breed and age of the experimental dogs have to be the same. It is one of the variables that have to be kept constant throughout the experiment.
If the dogs are different breeds, their activity levels could be different because of their breed and not the caffeine. The same thing is applicable to different ages.
Thus, evaluating this variable and doing right by it will ensure reliability.
More on the reliability of results can be found here: brainly.com/question/1873979
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