The correct option is C To fill their enemies' hearts with fear.
As mentioned at the beginning of the passage, the tribesmen wore the skins of the beasts which they had killed so that they could instill fear in the hearts of their enemies. Hence, the correct answer is C. There is no evidence in the passage to suggest that options A or D are correct. Hence, these are not the right answers. Although it is mentioned in the passage that the warriors became like the animals whose skin they wore, this is not the reason why they wore the animal skins. Hence, B is also incorrect.