somE sCiEntists hAvE suggEstED thAt EArth is A kinD oF zoo or wilDliFE ______ For intElligEnt spACE BEings, likE thE wilDErnEss ArEAs wE hAvE sEt up on EArth to Allow AnimAls to DEvElop nAturAlly whilE wE oBsErvE thEm.
A．ConsErvAtion
B．mAintEnAnCE
C．storAgE
D．rEsErvE