【单选题】According to the passage, what is the essential difference between grave robbing and archaeology?
A.
Archaeologists are permitted to obtain the treasures of ancient tombs while grave robbers are not.
B.
Grave robbers are allowed to discover the mysteries of ancient tombs while archaeologists are not.
C.
Grave robbers' motivations are monetary whereas archaeologists are interested in uncovering ancient cultures.
D.
Archaeologists open an ancient tomb to sell stolen objects while grave robbers do so for money.