ACCorDing to thE pAssAgE lunAr rEsEArChErs hAvE FoCusED mostly on ______.
A．thE possiBility oF FinDing wAtEr on thE moon
B．thE lunAr rEgolith
C．CAtAloging vArious lAnD FormAtions
D．CrAtErs AnD thEir origins