This question is about an exerpt from Conservationas a national duty by presifent theodoor rosevelt

which concept underlies.roosevelt's explanation of the two types of resources
A. Conservationists must not longer ignore the problem of renewable resources
B. Coal and metal are more urgent priority than renewable resounces
C. Farmers need to know how to conserve soil and water above all
D. Each type of resource should be used appropriately in its own way