I believe the answer is b) slowly heating the surface
4200000 is your answer hope this helps
Answer:
The frequencies are 
Explanation:
From the question we are told that
The length of the ear canal is 
The speed of sound is assumed to be 
Now taking look at a typical ear canal we see that we assume it is a closed pipe
Now the fundamental harmonics for the pipe(ear canal) is mathematically represented as

substituting values


Also the the second harmonic for the pipe (ear canal) is mathematically represented as
substituting values
Given that sound would be loudest in the pipe at the frequency, it implies that the child will have an increased audible sensitivity at this frequencies
Actually, when the refrigeration liquid is vaporized, the cooling effect is produced
Answer:Comparison of the embryological development of different species also reveals similarities that show relationships not evident in the fully-formed anatomy.
Explanation: