I would say
a. biological pest control
biological pest control is when other plants or animals are used to control pests. There are no chemicals used only the natural roles of the environment.
Hope this helped!
<span>Some scientists have presumed
that nature of life may exist with the choice
dictated by the local environment<span>. The primitive
earth illustrated the evolution of the
first heterotrophs from aggregates of organic molecules from the development of
heterotrophic forms according to the existing environmental conditions.</span></span>
<span>The Leeward side of a mountain range is in fact in a rain shadow. A rain shadow is an area of elevation where little to no rain falls, due to precipitation being forced out of passing clouds on the windward side of the mountain. Precipitation condenses as clouds rise over the mountain, and in general it precipitates as it crests over the mountain, leaving no moisture for the leeward side. An example of this is the American west, just west of the Rockies, where little to no rain falls.</span>
