Answer:
C
Explanation:
If you have more than one variable then you wont know which variable caused the change. Hope this helped, if it did give it a thanks or whatever.
Answer:
The tuba
Explanation:
The tuba produces sound by vibrating or buzzing the lips into a large cupped mouth piece. It produces different pitches by changing the mouthpiece.
Space is filled with nothing.
Space is the absence of matter.
Hope this helped
Answer: polar ice caps form
Explanation: