The doppler effect suggests that sound waves are relative to the observer. you know if an object is coming or going from the sound it makes. light waves follow the doppler effect also. however, instead of sound changing, you know if an object is coming or going

The light waves also follow the Doppler effect. However, instead of changing the sound, you know whether an object is coming or going through the brightness of the light.

Explanation:

The doppler effect is a physical phenomenon. This phenomenon allows us to perceive if an object is approaching or moving away through the wave effect that that object produces in relation to an observer. This is because when a wave is propagated the speed of that wave depends on the environment in which it is being emitted. For this reason, the speed of this wave will be constant even if the observer moves, but the frequency and movement of this wave varies in relation to the observer's position. In this case, the Doppler effect suggests that the sound waves are relative to the observer. You know if an object is coming in or out of the sound it produces. The light waves also follow the Doppler effect. However, instead of changing the sound, you know whether an object is coming or going through the brightness of the light.

sex cells are usually half's then they find another half and make a fertilize egg

d. planting trees

the trees take in carbon to make oxygen.