Answer:
A). The others are being preserved.
Explanation:
According to the given passage 'Mounds of History' by Elizabeth Kibler, the most likely reason for only Mound C being dug up would be that 'others are being preserved' which is reflected by the statements like 'Mound A at Etowah..reserved for the chief'. The description of 'only mound fully dug up..Mound C in which jewelry and relics have been found by the scientists' reveal that the other mounds are not yet dug and being conserved for varied purposes. Thus, option A is the correct answer.
