Concept:Use among when something is shared or distributed within a group of more than two people.Explanation:The sentence describes Okoye’s family members planning to share his wealth among themselves.Family members form a group of more than two people.The preposition among is used for a group, while between is only used for two persons or things.The words with and to do not fit the meaning of internal distribution among a group.Therefore, the correct word to complete the sentence is among.Answer:C. among