During a controlled experiment, a scientist will isolate and test (D) a single variable. A conclusion, nor a mass of information can be isolated or tested. A control group is the group that would receive a placebo, so testing that would be futile.
The tilt of earth's axis and earth's revolution around the sun hope i helped
I think mutation so D. If not then A
The recommendation of health professionals is to drink 8-10 glasses of water daily. But this is dependent on the climate and the activity the person is engaged into. For instance, an athlete who is training needs to drink more water to replace all the water lost in his body during training than compared to a person not training or exercising.