The answer to this is C- electromagnetic waves.
Hope that helps :)
The last one, wind blowing for a long time wont cause much wind, but if the wind is short and choppy, it will cause the waves to be choppy.
That is a chemical change or reaction.
The stem of the plant should be cut at least three to four centimeters above the surface level.
The stem should be tightly fixed into the glass capillary.
All connection should be made air-tight by using paraffin.
Initial and final readings should be carefully noted.
