If the color of leaves on oaks usually changes in the autumn season, then what usually changes in the autumn season?

Answer choices:
- Something that can be auburn
 - looseness of dirt or compost
 - the looseness of soil
 - the color of leaves on oaks
 - a hemisphere is tilted away from the sun
 - Warm air moving into cold air
 - the male sex cells of plants
 - The bending of a ray of light

 

    the color of leaves on oaks      