Explanation:
1200 is your answer for this question
The answer is A. Commensalism. <span>Commensalism, in ecology, is a class of relationships between two organisms where one organism benefits from the other without affecting it. This was the briefest answer from Wiki. Hope it helps, and sorry I'm late.</span>
Answer:
A- Astronomical body
C- Galaxy
D- Comet
B- Moon
Hope this helps you! Have a great day!
The concept required to solve this problem is related to the wavelength.
The wavelength can be defined as the distance between two positive crests of a wave.
The waves are in phase, then the first distance is

And out of the phase when

Thus the wavelength is

Here,
Wavelength
If we rearrange the equation to find it, we will have



Therefore the wavelength of the sound is 20cm.
<span>You experience physiological changes and a feeling of fear simultaneously. Hope this helped!</span>