A、to CArry inFormAtion thAt woulD hElp DEtErminE ElEvAtion.
B．to proviDE ACCurAtE wEAthEr rEports.
C．to rElAy inFormAtion From sCiEntists ArounD thE worl
D、
D、to inDiCAtE whiCh routE thE mountAin ClimBErs shoulD tAkE.