D the correct answer is d
Our muscles are attached to our skeleton to help us move. If we had no skeleton then our muscles would hang limply, making it harder for us to move.
The answer is (B. Medium) because it has to travel through the ear drum evenly without busting it. Hope this helped :)
Living things are identifiable by:
- movement (even cellular or internal movement)
- growth and development
- response to stimuli
- reproduction
- use of energy
- cellular structure