If earth's orbital motion around the sun is key to the leaves of many trees changing colors, then what factor is instrumental behind the change of leaf colors during the year?

Answer choices:
- organisms and their habitat
 - global warming
 - Earth orbiting the Sun
 - Solar energy
 - scattered light
 - Greenhouse gases
 - Varying light output from sun
 - Moon orbiting the Earth

 

   Earth orbiting the Sun       