Answer:
look if its at school
Explanation:
just ask teacher to help because if we say you will not learn
just say to teacher"pls can you help me with this and everything you
don't understand
C. Wavelength is the length of one complete wave cycle 
Wavelength of a sine wave, λ, can be measured between any two points with the same phase, such as between crests, or troughs, or corresponding zero crossings as shown
Answer:
as you increase in altitude, air pressure decreases
