Cottonwood, Aspen, and Willow Trees Have Drab- Coloured Flowers with No

Cottonwood, aspen, and willow trees have drab- coloured 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 pollen is dispersed by wind.
B) Early spring birds are probably the pollinators.
C) Their insect pollinators are probably colour blind.
D) Flower colour or shape is not related to pollinators.