Which of the following is an example of gene flow?
A. A forest fire kills 50% of red-spotted chipmunks in a forest community.
B. Pollen from a yellow daisy travels across a stream and pollinates an orange daisy.
C. A bird with blue feathers is less camouflaged in the rainforest than a bird with green feathers.
D. Mice with heavy coats are able to survive the winter better than mice with thin coats.