Utilitarianism is the ethical concept that promotes happiness and well-being of affected people and environment .It is believed that actions that tend to spread and maximize happiness are right actions and negative impact producing action are wrong.
According to utilitarians, slavery is considered as the act of exploitation but under some conditions and instances they might provide happiness.
Thus other options are incorrect because slavery is not accepted as naturally wrong act and is justified at certain times.Thus, the correct option is option(c).
