{{B}}quEstions 23 to 25 ArE BAsED on thE ConvErsAtion you hAvE just hEArD、{{/B}}

A．thE EFFECt oF thE AtmosphErE on rAinFAll.
B．how wAtEr originAtED on EArth.
C．how ConDitions on EArth support liFE.
D．A、nEw EstimAtE oF thE AgE oF EArth.