What Did American Pilots in Vietnam Primarily Imply When They

What did American pilots in Vietnam primarily imply when they satirically quipped "Only you can prevent forests"?

A) Harmful defoliants like Agent Orange were sprayed on trees in order to expose Vietcong hideouts.
B) Napalm dropped in jungles burned large acreage of forests and jungles.
C) Trails were cleared through the jungles of South Vietnam so that American troops could conduct search-and-destroy missions.
D) Bombs and missiles dropped in the jungles destroyed much of the native vegetation.