D.) Keep your head up while your skating.
Sound waves are sent out buy the animal/or vessel using sonar and the animal/vessel uses the echo from the original Soundwave that was sent out to determine the distance and size of the object that it hit
I wanted to help but I can’t read the article.
B it is b because it says community. it is a specialized community most likely elder home. if it were c or d it would say something about the hospital.