The author urges that the works of man be removed below the level of the natural world of the burrowing animals. What is implied here is that .
A.
man would find greater comfort and security below that level
B.
to build houses and passages above that level would call for larger amounts of money
C.
their natural habitat should be left intact so as to maintain ecological stability
D.
man would still want to occupy the surface with his farms, his forests and so on