The answer is option D. We have no way of knowing the number of revolutions of the planets.
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Positive - Due to urbanization, the people of rural areas settle in urban cites. These reduces the labour work which was done in rural areas and as they get water and electricity. The reduced labour work help them in maintaining their physical health
Negative - If people continues to enjoy the facilities and sit ideally doing nothing is much more worse than the above one. It causes obesity and can ultimately lead to heart attack
A constant factor could be the dose of the drugs and the species of the rats used.
<h3>What is a constant factor?</h3>
In an experiment, a constant factor is one that is not allowed to change al through the experiment. This one must be held as the same and not allowed to vary. A constant factor could be the dose of the drugs and the species of the rats used.
The factor that would be different for the experimental group and the control group the administration of the new drug.
Learn more about experiment:brainly.com/question/11256472
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