Answer:
D
Explanation:
I hope you get a good grade!
B- lack of control.
the scientists did not have a proper control group.
The frequency of a wave is the number of waves that passes through a point in a certain time. The less waves that pass in a period of time the lower the frequency of the wave. The more waves that pass in a period of time the higher the frequency of the wave. When measuring wave length the time period used is usually one second.
Yes .because the larger or more amount of pressuer will make moer of a compact . than a smaller one would