The Reason That Deciduous Leaves Turn Bright Colors in the Fall

The reason that deciduous leaves turn bright colors in the fall is

A) chlorophyll is converted into bright carotenoid pigments.
B) when chlorophyll breaks down, the remaining pigments become visible.
C) it is a chemical reaction involving the formation of ice crystals.
D) bright pigments are shifted from the roots and stem to the leaves while sugars and chlorophyll are pumped down to the roots.
E) a shift in the reflectance values of light is caused by the sun being lower in the sky; all leaf pigments actually remain the same.