The best answer is D because construction would be bad for the environment and take up space on the soil that is trying to be preserved. Also, for C, planting only one crop type in soil is not very beneficial to the soil at all. IT is best to plant multiple crops in the soil and move the crops to different parts of the soil each year when planting them.
The cardiorespiratory system gets stronger
That would be B.
When u have a larger population at hand the chances of your predictions being right are higher. So for example if he predicted a 3:1 ratio(yellow to green peas) he’d have a higher chance of seeing this ratio in a larger population than he would in a smaller one.
An experiment or survey must be controlled in order to receive accurate results.
In an experimental group, the independent variable is changed. But in the control group, the independent variable stays the same.