Lodestones were once used
A. heal people
B. pull nails from ships
C. point the way north in early compasses
D. all of the above

C. point the way north in early compasses

Explanation:

plato users

given bodies of water

pacific / arctic / indian / southern

[ a ] the caribbean sea

[ b ] the northern ocean

[ c ] the atlantic ocean

[ d ] the barents sea

with this being the given answers

allowed for the prediction of the properties of missing elements.