Which option is the best action for the forest surveyors to take in the following scenario?

A group of forest surveyors discovers a section of a forest that is dying. They check the trees and discover that a strain of disease has caused them to die. Even though the saplings look like they are dying, they discover that the saplings and plants on the ground are not diseased, just malnourished.

The surveyors hire a group of loggers to bulldoze the entire section of forest and let the forest regrow as it naturally would.
The surveyors decide to cut down all the plants and construct new buildings on the land rather than regrow in a diseased area.
The surveyors hire a group of loggers to cut down the diseased trees in order to allow the plants and saplings to receive light and nutrients.
The surveyors decide to leave the area in its current condition, which will allow the forest to handle the tree disease as it naturally would.