Answer:
A. Is the one that the experimenter manipulates directly
Explanation:
The independent variable is the one that is manipulated during an experiment by the experimenter.
The dependent variable is the one that is effected by the independent variable in an experiment.
There are plates under the surface that shift when there is interruption on the surface <span />
Longer the air column is the more harmonics are created. due to the longer column the waves have more space to bounce off of the sides of the column to create more harmonics.
