whAt is FounD to hAvE ClosE rElAtionship with rApiD inCrEAsE in populAtion
A．wAr BEtwEEn 2 CountriEs.
B．wAys DisCovErED to inCrEAsE proDuCtivity.
C．migrAtion From A ContinEnt to AnothEr ContinEnt.
D．A nEw rEligion BEginning to BE ACCEptED By pEopl