What would a conservation biologist say is the smartest ecological and economic way to protect trees from insects and disease? 

A)  Use antibiotics for only the infected trees. 
B)  Develop disease-resistant tree species. 
C)  Maintain the biological diversity of the forest. 
D)  Clear-cut and burn all infected areas.

Biological Diversity

The variety of life in all its forms and levels of organization, including ecosystem, species, and genetic diversity.

Conservation Biologist

A scientist who studies methods to protect, preserve, manage, and restore natural habitats and species.

Disease-Resistant

Having the ability to prevent disease or minimize its impact due to inherent characteristics or immunity.