In the story, it means the pursuit is carried on by hunting dogs
The story said that when trying to capture the slaves, the hunters use tracking dogs to track off the runaway slaves.
I think the answer is 'purity' as it makes the most sense. Purity is represented by the color white, while green is either jealousy or happy/calming(rebirth). New ideas can be symbolized by green, as in a green flag or a green light.
<span>They are colors directly opposite each other in the color spectrum, such as red and green or blue and orange</span>
