Final answer:
In "December 2001: The Green Morning," the new trees and greenery on Mars symbolize transformation, hope, and the possibility of creating a more livable environment.
Step-by-step explanation:
The new trees and greenery on Mars in the story "December 2001: The Green Morning" symbolize the desire for transformation and the hope for a better future. Benjamin Driscoll's goal of making Mars green reflects his aspiration to create a more hospitable and livable environment on the planet. The trees and greenery represent the potential for change and the possibility of turning a barren planet into a lush and vibrant world.