Social researchers generally study ethics. they study human psychology for example. if they are biased in their surveys, that is not an ethical consideration.
If you wanted to increase the rate of photosynthesis in a plant, you would develop a plant with many, broad leaves. This helps to get more sunlight. The correct answer is C, many, broad leaves.
Sorry I am a week late in answering this but it helps people later. The answer I got was this:
Groundwater is an important source of freshwater, partly because it accounts for approximately 30% of the Earth's freshwater.
I know this is a little late but I hope it helps you later on.
