Cottonwood,aspen,and Willow Trees Have Drab-Colored Flowers with No Petals That

Cottonwood,aspen,and willow trees have drab-colored flowers with no petals that appear before the tree's leaves are out in the spring;they are dioecious.What does that indicate about these trees?

A) Their insect pollinators are probably color blind.
B) Early spring birds are probably the pollinators.
C) Their pollen is dispersed by wind.
D) Flower color or shape is not related to pollinators.