Amarine biologist is studying dolphin calls and notices that sometimes the calls sound louder based on the background noise in the water. what wave property of the dolphin's call is changing because of the background noise?
1.amplitude
2.frequency
3.speed
4.wavelength

Option C, Speed

Explanation:

Sounds travel faster in water. Their speed in water is five times of their speed in air.  

With such high speed, sound waves instead of going through ossicles bones (in the inner ears) directly vibrate the heavy bone behind the ears. Due to this reason, a person below water hears sound waves of higher frequency.  

However, while travelling through air sound waves reaches at lower frequency

Hence, option C is correct

the sphincter muscles at the end of the digestive tract is the anus.

the answer for this question would be d. glaciers